Tamilnet Live: Systems Administrator Interview Question & Answer

Systems Administrator<=>Interview Question & Answer
Reference

http://computernetworkingnotes.com/

What is router?

What is switch?

What is hub?

What isTCP/IP?

What is active directory?

What is IIS?

What is DNS?

What is DHCP?

What is Microsoft Exchange Server?

What is FTP?

What is OSI MODEL?

What is Firewall?

What is firewall?

A firewall is a hardware or software installed to provide security to the private networks connected to the internet. They can be implemented in both hardware and software, or a combination of both. All data entering or leaving the Intranet passes through the firewall which allows only the data meeting the administrators’ rules to pass through

What are the types of firewalls?

Packet Filtering Firewall:
This type of Firewall detects packets and block unnecessary packets and makes network traffic release.

Screening Router Firewalls:
It's a software base firewall available in Router provides only light filtering.

Computer-based Firewall:
It's a firewall stored in server with an existing Operating System like Windows and UNIX.

Hardware base Firewall:
Its device like box allows strong security from public network. Mostly used by big networks.

Proxy Server:
Proxy server allows all clients to access Internet with different access limits. Proxy server has its own firewall which filters the all packet from web server.

Latest answer: NetBIOS (Network Basic Input/Output System) Protocol allows applications on separate computers to communicate over a LAN. It runs over TCP/IP giving each computer in the network a NetBIOS name and IP address.................
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What is IGMP protocol?

Latest answer: Internet Group Management Protocol, allows internet hosts to multicast. i.e. to send messages to a group of computers. There may be a group of internet hosts interested to multicast..................
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Explain PPP protocol.

Latest answer: Point to Point protocol helps communication between 2 computers over a serial cable, phone line or other fiber optic lines. E.g. Connection between an Internet Service Provider and a host..................
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What is TCP/IP protocol?

Latest answer: Transmission Control Protocol / Internet Protocol: - It is a family of protocols used for communication and connection between hosts on the internet. It is the most widely used standard for transmitting data over the internet...............
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What is FTP (File Transfer Protocol)?

Latest answer: FTP is File Transfer Protocol. It used to exchange files on the internet. To enable the data transfer FTP uses TCP/IP, FTP is most commonly used to upload and download files from the internet..................
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What is HTTP (Hypertext Transfer Protocol)?

Latest answer: HTTP or Hyper Text Transfer Protocol is provides a set of rules to transfer files, videos, images over the world wide web. When the web browser is opened, a HTTP request call is made..................
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What is NNTP (Network News Transfer Protocol)?

Latest answer: NNTP or Network News Transfer Protocol is used to manage the notes posted on Unset newsgroup (a collection of posted notes on a subject posted by different users)...............
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What is SMTP (Simple Mail Transfer Protocol)?

Latest answer: SMTP or Simple Mail Transfer Protocol is used to send email messages between servers. The messages are retrieved using email clients. SMTP is more commonly used to send messages from a mail client to a mail server.................
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What is POP3 (Post Office Protocol 3)?

Latest answer: POP3 or Post Office Box 3 is used fro receiving emails. It is a client server protocol which holds the email.................
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What is SNMP (Simple Network Management Protocol)?

Latest answer: SNMP or Simple Network Management Protocol is typically used for managing the network. Managing the network includes managing the nodes present in the network................

What are the difference between hub and switch?

Hub is a layer 1 device. It will out the signal from all of its port except the one from where its insert. It is unable to detect the collision. It works on single collision and single broadcast domain.
Switch is layer 2 device. It maintains a CAM table that store the MAC address of devices attached on its port. CAM table is used to make the forwarding decision. It works on per port collision and single broadcast domain.

What is layer?

Layer is a completely logical partition of PDU (protocol data unit) process. That define how the information is travel form one computer to other over the network.

What is TCP/IP?

It is combination of two protocols TCP and IP. It is used for reliable data transfer.

What is operating system?

An operating system (sometimes abbreviated as "OS") is the program that, after being initially loaded into the computer by a boot program, manages all the other programs in a computer. It provides a platform to application software.

What is package software?

The collection of mostly used software released in package Form Company. For Example Ms-Office that contain word, power point, Excel, etc.

Full form of .co.in, .com

COM - ".com" stands for "commercial".

NET - ".net" stands for "network"

ORG - ".org" stands for "organization"

INFO - ".info" stands for "information"

BIZ - ".biz" stands for "business".

IN - 'IN' stands for India. The 'IN'

is a 2-letter country code for India.

What is ring topology?

In a ring topology, device one connects to device two, device two connects to device three, and so on to the last device, which connects back to device one.

Which cable is used in LAN?

Generally coaxial and TP media is used in LAN networking.

What are Difference between STP and UTP?

STP cable is mostly used by IBM; it has an extra cover over each pair.
UTP cable is used in star topology. It has a single cover over all pair.

What is IEEE?

The Institute of Electrical and Electronics Engineers or IEEE (read eye-triple-e) is an international non-profit, professional organization for the advancement of technology related to electricity. It has the most members of any technical professional organization in the world, with more than 365,000 members in around 150 countries.

What is 802.3?

IEEE 802.3 is a collection of IEEE standards defining the physical layer and the media access control (MAC) of the data link layer of wired Ethernet. Physical connections are made between nodes and infrastructure devices hubs, switches and routers by various types of copper or fiber cable.

Full form of ping.

PING stand for Packet Internet Grouper

What are the minimum requirements for xp installation?

64MB RAM
1.5GB free HDD space
233MHz minimum processor.

What are 10Base2, 10Base5 and 10BaseT Ethernet LANs?

10Base2— An Ethernet term meaning a maximum transfer rate of 10 Megabits per second that uses baseband signaling, with a contiguous cable segment length of 100 meters and a maximum of 2 segments.
10Base5—An Ethernet term meaning a maximum transfer rate of 10 Megabits per second that uses baseband signaling, with 5 continuous segments not exceeding 100 meters per segment.
10BaseT—An Ethernet term meaning a maximum transfer rate of 10 Megabits per second that uses baseband signaling and twisted pair cabling.

What is the difference between an unspecified passive open and a fully specified passive open?

An unspecified passive open has the server waiting for a connection request from a client.
A fully specified passive open has the server waiting for a connection from a specific client.

Explain the function of Transmission Control Block

A TCB is a complex data structure that contains a considerable amount of information about each connection.

What is a Management Information Base (MIB)?

A Management Information Base is part of every SNMP-managed device. Each SNMP agent has the MIB database that contains information about the device's status, its performance, connections, and configuration. The MIB is queried by SNMP.

What is anonymous FTP and why would you use it?

Anonymous FTP enables users to connect to a host without using a valid login and password. Usually, anonymous FTP uses a login called anonymous or guest, with the password usually requesting the user's ID for trackingpurposes only. Anonymous FTP is used to enable a large number of users to access files on the host without having to go to the trouble of setting up logins for them all. Anonymous FTP systems usually have strict controls over the areas an anonymous user can access.

What is a pseudo tty?

A pseudo tty or false terminal enables external machines to connect through Telnet or rlogin. Without a pseudo tty, no connection can take place.

What does the Mount protocol do?

The Mount protocol returns a file handle and the name of the file system in which a requested file resides. The message is sent to the client from the server after reception of a client's request

What is External Data Representation?

External Data Representation is a method of encoding data within an RPC message, used to ensure that the data is not system-dependent.

What is Full form of ADS?

Active Directory Structure

How will you register and activate windows?

If you have not activatedwindows XP, you can do so at any time by clicking the windows Activation icon in the system tray to initiate activation. Once you have activated windows XP, this icon

disappears from the system tray.
For registration
Start ==> Run ==>regwiz /r

Where do we use cross and standard cable?

Computer to computer ==> cross
Switch/hub to switch/hub ==>cross
Computer to switch/hub ==>standard

How many pins do serial ports have?

In computer it’s known as com port and could be available in 9pin or 25 pin. On router it have 60 pins.

How will check ip address on 98?

Start ==> Run ==> command ==>winipcfg

How will you make partition after installing windows?

My computer ==> right click ==> manage ==>disk management ==>
select free space ==> right click ==> New partition

What is IP?

It’s a unique 32 bits software address of a node in a network.

What is private IP?

Three ranges of IP addresses have been reserved for private address and they are not valid for use on the Internet. If you want to access internet with these address you must have to use proxy server or NAT server (on normal cases the role of proxy server is played by your ISP.).If you do decide to implement a private IP address range, you can use IP addresses from any of the following classes:
Class A 10.0.0.0 10.255.255.255
Class B 172.16.0.0 172.31.255.255
Class C 192.168.0.0 192.168.255.255

What is public IP address?

A public IP address is an address leased from an ISP that allows or enables direct Internet communication.

What’s the benefit of subnetting?

Reduce the size of the routing tables.
Reduce network traffic. Broadcast traffic can be isolated within a single logical network.
Provide a way to secure network traffic by isolating it from the rest of the network.

What are the differences between static ip addressing and dynamic ip addressing?

With static IP addressing, a computer (or other device) is configured to always use the same IP address. With dynamic addressing, the IP address can change periodically and is managed by a centralized network service

What is APIPA?

Automatic private IP addressing (APIPA) is a feature mainly found in Microsoft operating systems. APIPA enables clients to still communicate with other computers on the same network segment until an IP address can be obtained from a DHCP server, allowing the machine to fully participate on the network. The range of these IP address are the 169.254.0.1 to 169.254.255.254 with a default Class B subnet mask of 255.255.0.0.

What are the LMHOSTS files?

The LMHOSTS file is a static method of resolving NetBIOS names to IP addresses in the same way that the HOSTS file is a static method of resolving domain names into IP addresses. An LMHOSTS file is a text file that maps NetBIOS names to IP addresses; it must be manually configured and updated.

What is DHCP scope?

A scope is a range, or pool, of IP addresses that can be leased to DHCP clients on a given subnet.

What is FQDN?

An FQDN contains (fully qualified domain name) both the hostname and a domain name. It uniquely identifies a host within a DNS hierarchy

What is the DNS forwarder?

DNS servers often must communicate with DNS servers outside of the local network. A forwarder is an entry that is used when a DNS server receives DNS queries that it cannot resolve locally. It then forwards those requests to external DNS servers for resolution.

Which command will you use to find out the name of the pc in networks?

NSLOOKUP [192.168.0.1]
[Ip of target computer]

How will enable sound service in 2003?

By default this service remain disable to enable this service
Start ==> administrative tools ==> service ==> windows audio ==> start up type ==> automatic

How will enable CD burning service in 2003?

By default this service remain disable to enable this service
Start ==> administrative tools ==> service ==> IMAPI CD burning com service ==> start up type ==> automatic

How to change settings in command prompt?

How to start DirectX Diagnostic Tool ?

To start the DirectXDiagnostic Tool: 1. Click Start, and then click Run.
In the Open box, type dxdiag and then click OK.

How to determine whether there is an issue with the DNS configuration of your connection to your ISP?

At a command prompt, type ipconfig /all and then press ENTER to display the IP address of your DNS server. If the IP address for your DNS server does not appear, you need contact your ISP.

What do you need to do that your browser will point URL www.example.com to the internal IP address 127.99.11.01?

Make changes in the hosts file in C:\WINDOWS\system32\drivers\etc
The Hosts file is looked at first before going out to the DNS (Domain Name Service) servers. you have to put the following on new lines at the end of hosts file:
127.99.11.01 example.com
127.99.11.01 www.example.com

What can you suggest to enhance testing process on windows OS?

Put shortcut to notepad.exe in SendTo folder. It is speed up work with different files like hosts, configuration files. Location of this folder is
C:\Documents and Settings\Default User\sendto.
Open it and create shortcut of notpad.exe

What is FTP?

FTP is short for File Transfer Protocol. This is the protocol used for file transfer over the Internet.

How will you make XP home the client of server 2003?

XP home edition is made only for home purpose so we can’t use it as the client. And same rule apply on windows vista editions also.

Where do you take back up from?

Click Start, point to All Programs, point to Accessories, point to System Tools, and then click Backup.
Bedside’s it?
If OS support then Select Drive ==> properties ==> back up now

What is router?

Router is a device that is used to connect two different networks.

How will you configure ADS?

Start ==> Run ==> DCPROMO
Or
Start==>Configure your server ==> add/Remove a Role

What is ADS?

A central component of the Windows platform, Active Directory service provides the means to manage the identities and relationships that make up network environments.

What if this wizard (ADS) is not running?

Check the network cable it should be plugged
Check root partition it should be in NTFS
Check IP of server it should be configured statically

How will you add a client to server? /
How’s the client join a domain?
What are the client configurations?

On Server
Configure ADS (for example it’s configured with xyz.com)
On Client
Log in form local administrator account
My Computer ==> Properties ==> Computer Name ==> Change
==>Domain ==>xyz.com ==> username Administrator (of xyz.com)
Password xxxxxxxxxxx (of admin of xyz.com)
Welcome to xyz.com ==> Restart the computer

Does it necessary to use administrator account to configure the client?

Not every time but you are required a properly configured user account in domain controller security policy.

ISO stand for?

International standard organization

OSI stand for?

Open System Interconnection

What is full form DHCP and how will you configure it?

Dynamic host configuration protocol

To configure it on Server
Configure your server ==>Add/Remove a role ==>DHCP server ==>complete the wizard
Start ==> Administrative tools ==> DHCP ==>New scope ==> Wizard
Now authorized this server and do activate it
On client
Local area network ==>tcp/ip ==> obtain ip automatically
Obtain DNS automatically

Difference between XP home and XP professional ?

Feature that is not available in XP home edition
Remote Desktop
Off line file and folder
Encrypting file system
Group policy
Roaming profile
Remote installation
Joining Domain
The features listed above are only available in XP professional

Which OSI layer does IP belong?

P belongs to the Network Layer (layer 3) in the OSI model.

What is a subnet mask?

Subnet mask is a 4 byte (32 bit) number used to identify the sub-network ID and the host ID from an IP address. All the hosts in a sub-network will have the same subnet mask. E.g. 255.255.255.0, 255.255.127.0, 255.255.0.0

How many times computer reboot when server 2000 install?

2 times.

How will you remove this error “ ntldr missing press any key to reboot the system” ?

Reboot the system with XP, ( apply also on server2003,) cd
On setup screen press to R to repair the window
Now provide the administrator password
C:\>cd f:( your cd drive latter, f is taken as the example )
f:\>cd i386
f:\>copy ntldr c:\
f:\>exit
reboot the system

Why do we do networking?

For data sharing
To accumulate hardware resource

What are the benefits of networking?

There are lots of advantages from build up a network, but the three big facts are-
File Sharing From sharing files you can view, modify, and copy files stored on a different computer on the network just as easily as if they were stored on your computer.
Resource Sharing
Resources such as printers, fax machines, Storage Devices (HDD, FDD and CD Drives), Webcam, Scanners, Modem and many more devices can be shared.
Program Sharing
Just as you can share files on a network, you can often also share program on a network. For example, if you have the right type of software license, you can have a shared copy of Microsoft Office, or some other program, and keep it on the network server, from where it is also run

What is network?

A network is basically all of the components (hardware and software) involved in connecting computers across small and large distances.

What is networking?

A process that is describes how the network will connect.

What is topology?

A topology defines how the devices are connected. Further it is divided in physical and logical topology.

What is difference between physical and logical topology?

A physical topology describes how devices are physically cabled together.
A logical topology describes how devices communicate across the physical topology

How many types of topology are available?

A point-to-point topology has a single connection between two devices.
In a star topology, a central device has many point-to-point connections to other devices.
A bus topology uses a single connection or wire to connect all devices.
In a ring topology, device one connects to device two, device two connects to device three, and so on to the last device, which connects back to device one.

Name of seven layers in Open System Interconnection model.

They are Application, Presentation, Session, Transport, Network, Data link, and Physical.

What is the difference between ARP and RARP?

The address resolution protocol (ARP) is used to associate the 32 bit IP address with the 48 bit physical address, used by a host or a router to find the physical address of another host on its network by sending a ARP uery packet that includes the IP address of the receiver.
The reverse address resolution protocol (RARP) allows a host to discover its Internet address when it knows only its physical address.

What is Client/Server?

Clients and Servers are separate logical entities that work together over a network to accomplish a task. Many systems with very different architectures that are connected together are also called Client/Server.

What is MAC address?

It is the 48 bit hardware address of LAN card. MAC address is usually stored in ROM on the network adapter card and it is unique.

What are the perquisites to configure server?

LAN card should be connected:

Root (partition on which window is installed) should in NTFS

Server should be configured with a static IP address

How we will configure ADS?

Start ==> RUN ==> DCPROMO

How will you test LAN card?

Ping 127.0.0.1
If getting reply its fine

What are the difference between DOMAIN and WORKGROUP?

Workgroup:-
(i)Every PC is responsible for its security own.
(ii)No centralize administration
(iii)Main aim to save hardware recourse
(iv)Best suite in school, training institute, cyber café
Domain: -
(i)Server is responsible for data safety.
(ii)Centralize administration
(iii)Main aim is to secure data
(iv)Best suite in company environments

Which command is used to check the IP address of your system?

ipconfig

Which set wizard will run to do peer to peer networking in XP?

Small home and office setup wizard

Which command is used to check the physical connectivity between two computers?

Ping

What is map drive?

A special feature that will map network resource to my computer.

What is Proxy Server?

Most large businesses, organizations, and universities these days use a proxy server. This is a server that all computers on the local network have to go through before accessing information on the Internet. By using a proxy server, an organization can improve the network performance and filter what users connected to the network can access.

Which folder contains ADS installed on server?

NTDS

What is the full form of Internet?

International Networking

Which are the bootable files of 98 and XP ?

In windows98 it is command.com
In XP it is NTLDR

In which partition Linux is installed ?.

Linux doesn’t support windows file system that contain partition scheme. It (Linux) has its own file system known as ext2, and ext3. it will install only on it.Inlinux file system it will install on / (root) partition.

What is size of SWAP ?

It’s the hard disk space that is used as RAM for fast processing. In window it’s known as virtual memory and could be set as per retirement via this path
My Computer ==>properties ==>advance
In Linux it’s known as SWAP space and generally taken the double size of physical RAM For example if you have 256 (MB) DDR physical ram then swap space would be 512 MB.

What is full form of C.M.O.S ?

Complementary metal oxide semiconductor

How will you check ip address without using network place ?

Start ==> Run ==> Command ==>ipconfig

What is IP?

Internet Protocol (IP) is an unreliable, best effort delivery, connection-less protocol used for transmitting and receiving data between hosts in a TCP/IP network

What is difference between Half-Duplex and Full-Duplex Communications?

In half-duplex communication data travels in only one direction at a time.

In full-duplex mode two systems that can communicate in both directions simultaneously are operating.

Which is the most popular international cable standard?

TIA/EIA-568-B

Describe UTP cable

UTP cable comes in a variety of different grades, called "categories" by the Electronics Industry Association (EIA) and the Telecommunications Industry Association (TIA), the combination being referred to as EIA/TIA.

Cat 1 :- Used for voice-grade telephone networks only; not for data transmissions

Cat 2 :- Used for voice-grade telephone networks

Cat 3 :-Used for voice-grade telephone networks, 10 Mbps Ethernet, 4 Mbps Token Ring,

Cat 4 :-Used for 16 Mbps Token Ring networks

Cat 5 :-Used for 100BaseTX Fast Ethernet, SONet, and OC-3 ATM

Cat 5e:- Used for Gigabit (1000 Mbps) Ethernet protocols

What is TIA/EIA?

A cooperative trade association responsible for the "Commercial Building Telecommunication Cabling Standard," also known as EIA/TIA 568, which specifies how network cables should be installed in a commercial site.

What is attenuation ?

The progressive weakening of a signal as it travels over a cable or other medium. The longer the distance a signal travels, the weaker the signal gets, until it becomes unreadable by the receiving system

What is Crosstalk ?

A type of signal interference caused by signals transmitted on one pair of wires bleeding over into the other pairs. Crosstalk can cause network signals to degrade, eventually rendering them unviable.

Where would you use cross and straight cable?

A straight-through cable is used for DTE-to-DCE connections.

1. A hub to a router, PC, or file server

2.A switch to a router, PC, or file server

Crossover cables should by used when you connect a DTE to another DTE or a DCE to another DCE.

1. A hub to another hub

2. A switch to another switch

3. A hub to a switch

4. A PC, router, or file server to another PC, router, or file server

Describe different types of connector used in LAN

RJ-11 ( Registered Jack-11) a four- or six-wire connector primarily used to connect telephone equipment.

RJ-45 (Registered Jack-45) connector is an eight-wire connector that is commonly used to connect computers to a local area network (LAN), particularly Ethernet LANs.

AUI(Attachment Unit Interface.) is the part of the Ethernet standard that specifies how a Thicknet cable is to be connected to an Ethernet card. AUI specifies a coaxial cable connected to a transceiver that plugs into a 15-pin socket on the network interface card (NIC).

BNC stand for British Naval Connector (or Bayonet Nut Connector or Bayonet Neill Concelman)a type of connector used with coaxial cables such as RG-58.BNC connectors are used on both Thicknet and Thinnet.

What is protocol?

A set of standards sets of standards that define all operations within a network. There are various protocols that operate at various levels of the OSI network model such as transport protocols include TCP.

Who develop the OSI modal?

The International Organization for Standardization (ISO) developed the Open Systems Interconnection (OSI) Reference Model to describe how information is transferred from one machine to another.

What is Micro segmentation?

Micro segmentation is a term used with switches when each networking device has its own dedicated port on a switch.

What are the advantages of OSI modal?

Defines the process for connecting two layers, promoting interoperability between vendors.

Separates a complex function into simpler components.

Allows vendors to compartmentalize their design efforts to fit a modular design, which eases implementations and simplifies troubleshooting

What are the port number / socket number and Connection Multiplexing?

Transport layer assigns a unique set of numbers for each connection. These numbers are called port or socket numbers TCP, and UDP, provide a multiplexing function for a device: This allows multiple applications to simultaneously send and receive data.

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Lan Card Test Sheet
Also know as Ethernet Card, or NIC Network interface card.
In device manage	Reason	In LAN card properties
Yellow sign	Driver not installed	Will not show
Red Cross	Disable	Show with disable status
No Ethernet option	Physical not installed	Will not show
At Command Prompt
C:/>ipconfig Possible out put
	IP address of computer	Everything is fine
	Windows ipConfiguration	Either media is disconnected or LAN disable
C:/> ping <Remote computerip>
Used to check the physical connectivity
Possible out put
	Reply From .....	Host is up and operational
	Request time out	Either firewall is on remote desktop or network plug is loose
	Destination net unreachable	There is no route to reach to the remote network

How will you make dial-up connection ?

Physical installation of modem ==>install modem driver ==> my network place ==> properties ==> Make new connection ==> next ==>connection to internet ==> setup my connection manually ==> Connect using a dial up modem

How will share printer ?

Install local printer on that pc which has physically attached printer. And then Right click on it ==> share ==>Inxp if you run small office set wizard it will be share automatically. On all other PC install network printer. While installing printer choose network printer.

How will you configure broadband ?

There are two type of broadband available

One that required user name and password to connect the internet like BSNL or Reliance for this type of connection Physical installation of modem ==> my network place ==> properties ==> Make new connection ==> next ==> connection to internet ==> setup my connection manually ==> Connect using a broadband connection that requires a user name and password ==> ISP name ==> User name and password ==> add a short cut to desktop
If you are using other type of connection like Airtel for this type of connection you don’t required any additional configuration
If DHCP is enable in modem
IP address and DNS setting will be automatically configure.
If DHCP is not enable then set it manually as given ip by provider

What is minimum requirement of RAM for installation of XP?

64 MB

What is firewall?

The primary method for keeping a computer secure from unauthorized user. A firewall allows or blocks traffic into and out of a private network or the user's computer. Firewalls are widely used to give users secure access to the Internet as well as to separate a company's public Web server from its internal network.
XP pack 2 has a built in firewall that is enabled by default. To change the setting of it use this path
Local area network ==> properties ==> advance ==> setting

What is Active Directory?

Active Directory is a network-based object store and service that locates and manages resources, and makes these resources available to authorized users and groups. An underlying principle of the Active Directory is that everything is considered an object—people, servers, workstations, printers, documents, and devices. Each object has certain attributes and its own security access control list (ACL).

Workers are not able to print from the printer, there user logon are correct and are allowed to print from that printer in active directory. How would you resolve this issue?

Verify printer is set as default.

Verify users have local privileges set properly to print.

Is print server delivering correct drivers.

Is local naming convention for printer correct.

If pre Win2000 workstation, naming convention must be less than 12 characters.

Make sure no viruses present. Some Viruses can shut down IPC shares and printing services.

Where are the Windows NT Primary Domain Controller (PDC) and its Backup Domain Controller (BDC) in Server 2003?

The scheme of PDC and BDC is replaced by The Active Directory in server 2000 and further. Now all domain controllers share a multi master peer-to-peer read and write relationship that hosts copies of the Active Directory.

How can group policy be refreshed?

Restart the server

Leave the server ideal for 90 minute

Run ==>gpupdate (server 2003 only)

What is LILO?

LILO stands for Linux boot loader. It will load the MBR, master boot record, into the memory, and tell the system which partition and hard drive to boot from.

I can’t seem to access the Internet, don’t have any access to the corporate network and on IP configuration on my address is 169.254.*.*. What happened?

The 169.254.*.* net mask is assigned to Windows machines running 98/2000/XP if the DHCP server is not available. The name for the technology is APIPA (Automatic Private Internet Protocol Addressing).

We’ve installed a new Windows-based DHCP server, however, the users do not seem to be getting DHCP leases off of it.

The server must be authorized first with the Active Directory.

What’s the difference between local, global and universal groups?

Domain local groups assign access permissions to domain groups for local domain resources. Global groups provide access to resources in entire domains.

What’s the major difference between FAT and NTFS on a local machine?

FAT and FAT32 provide no security over locally logged-on users. Only native NTFS provides extensive permission control on both remote and local files.

What is presentation layer and how it is responsible for in the OSI model?

The presentation layer establishes the data format prior to passing it along to the network application’s interface. TCP/IP networks perform this task at the application layer

What is Full form of ADS?

Active Directory Structure

How will you register and activate windows?

If you have not activatedwindows XP, you can do so at any time by clicking the windows Activation icon in the system tray to initiate activation. Once you have activated windows XP, this icon disappears from the system tray.
For registration
Start ==> Run ==>regwiz /r

Where do we use cross and standard cable?

Computer to computer ==> cross
Switch/hub to switch/hub ==>cross
Computer to switch/hub ==>standard

How many pins do serial ports have?

In computer it’s known as com port and could be available in 9pin or 25 pin. On router it have 60 pins.

How will check ip address on 98?

Start ==> Run ==> command ==>winipcfg

How will you make partition after installing windows?

My computer ==> right click ==> manage ==> disk management ==>
select free space ==> right click ==> New partition

What is IP?

It’s a unique 32 bits software address of a node in a network.

What is private IP?

What is public IP address?

A public IP address is an address leased from an ISP that allows or enables direct Internet communication.

What’s the benefit of subnetting?

What are the differences between static ip addressing and dynamic ip addressing?

What is APIPA?

What are the LMHOSTS files?

What is DHCP scope?

A scope is a range, or pool, of IP addresses that can be leased to DHCP clients on a given subnet.

What is FQDN?

An FQDN contains (fully qualified domain name) both the hostname and a domain name. It uniquely identifies a host within a DNS hierarchy

What is the DNS forwarder?

Which command will you use to find out the name of the pc in networks?

NSLOOKUP [192.168.0.1]
[Ip of target computer]

How will enable sound service in 2003?

By default this service remain disable to enable this service
Start ==> administrative tools ==> service ==> windows audio ==> start up type ==> automatic

How will enable CD burning service in 2003?

By default this service remain disable to enable this service
Start ==> administrative tools ==> service ==> IMAPI CD burning com service ==> start up type ==> automatic

What is a DNS resource record?

resource record is an entry in a name server's database. There are several types of resource records used, including name-to-address resolution information. Resource records are maintained as ASCII files.

What protocol is used by DNS name servers?

DNS uses UDP for communication between servers. It is a better choice than TCP because of the improved speed a connectionless protocol offers. Of course, transmission reliability suffers with UDP.

What is the difference between interior and exterior neighbor gateways?

Interior gateways connect LANs of one organization, whereas exterior gateways connect the organization to the outside world.

What is the HELLO protocol used for?

The HELLO protocol uses time instead of distance to determine optimal routing. It is an alternative to the Routing Information Protocol.

What are the three type of routing tables and What are the advantages and disadvantages of these?

A fixed central table lets a manager modify only one table, which is then read by other devices. The fixed central table reduces the need to update each machine's table, as with the fixed table. Usually a dynamic table causes the fewest problems for a network administrator, although the table's contents can change without the administrator being aware of the change.

What is source route?

It is a sequence of IP addresses identifying the route a datagram must follow. A source route may optionally be included in an IP datagram header.

What is RIP (Routing Information Protocol)?

It is a simple protocol used to exchange information between the routers.

What is SLIP (Serial Line Interface Protocol)?

It is a simple protocol used for transmission of IP datagrams across a serial line.

What is Proxy ARP?

It is using a router to answer ARP requests. This will be done when the originating host believes that a destination is local, when in fact is lies beyond router.

What is OSPF?

It is an Internet routing protocol that scales well, can route traffic along multiple paths, and uses knowledge of an Internet's topology to make accurate routing decisions.

What is Kerberos?

It is an authentication service developed at the Massachusetts Institute of Technology. Kerberos uses encryption to prevent intruders from discovering passwords and gaining unauthorized access to files.

What is a Multi-homed Host?

It is a host that has a multiple network interfaces and that requires multiple IP addresses is called as a Multihomed Host.

What is NVT (Network Virtual Terminal)?

It is a set of rules defining a very simple virtual terminal interaction. The NVT is used in the start of a Telnet session.

What is Gateway-to-Gateway protocol?

It is a protocol formerly used to exchange routing information between Internet core routers.

What is BGP (Border Gateway Protocol)?

It is a protocol used to advertise the set of networks that can be reached with in an autonomous system. BGP enables this information to be shared with the autonomous system. This is newer than EGP (Exterior Gateway Protocol).

What is autonomous system?

It is a collection of routers under the control of a single administrative authority and that uses a common Interior Gateway Protocol.

What is EGP (Exterior Gateway Protocol)?

t is the protocol the routers in neighboring autonomous systems use to identify the set of networks that can be reached within or via each autonomous system.

What is IGP (Interior Gateway Protocol)?

It is any routing protocol used within an autonomous system.

What is Mail Gateway?

It is a system that performs a protocol translation between different electronic mail delivery protocols.

What is wide-mouth frog?

Wide-mouth frog is the simplest known key distribution center (KDC) authentication protocol.

What is silly window syndrome?

It is a problem that can ruin TCP performance. This problem occurs when data are passed to the sending TCP entity in large blocks, but an interactive application on the receiving side reads 1 byte at a time.

What is region?

When hierarchical routing is used, the routers are divided into what we call regions, with each router knowing all the details about how to route packets to destinations within its own region, but knowing nothing about the internal structure of other regions.

What is multicast routing?

Sending a message to a group is called multicasting, and its routing algorithm is called multicast routing.

What is traffic shaping?

One of the main causes of congestion is that traffic is often busy. If hosts could be made to transmit at a uniform rate, congestion would be less common. Another open loop method to help manage congestion is forcing the packet to be transmitted at a more predictable rate. This is called traffic shaping.

What is packet filter?

Packet filter is a standard router equipped with some extra functionality. The extra functionality allows every incoming or outgoing packet to be inspected. Packets meeting some criterion are forwarded normally. Those that fail the test are dropped.

What is virtual path?

Along any transmission path from a given source to a given destination, a group of virtual circuits can be grouped together into what is called path.

What is virtual channel?

Virtual channel is normally a connection from one source to one destination, although multicast connections are also permitted. The other name for virtual channel is virtual circuit.

What is logical link control?

One of two sublayers of the data link layer of OSI reference model, as defined by the IEEE 802 standard. This sublayer is responsible for maintaining the link between computers when they are sending data across the physical network connection.

Why should you care about the OSI Reference Model?

It provides a framework for discussing network operations and design.

What is the difference between routable and non- routable protocols?

Routable protocols can work with a router and can be used to build large networks. Non-Routable protocols are designed to work on small, local networks and cannot be used with a router

What is MAU?

In token Ring , hub is called Multistation Access Unit(MAU).

Explain 5-4-3 rule

In aEthernet network, between any two points on the network, there can be no more than five network segments or four repeaters, and of those five segments only three of segments can be populated.

What is the difference between TFTP and FTP application layer protocols?

The Trivial File Transfer Protocol (TFTP) allows a local host to obtain files from a remote host but does not provide reliability or security. It uses the fundamental packet delivery services offered by UDP.
The File Transfer Protocol (FTP) is the standard mechanism provided by TCP / IP for copying a file from one host to another. It uses the services offered by TCP and so is reliable and secure. It establishes two connections (virtual circuits) between the hosts, one for data transfer and another for control information.

What is the minimum and maximum length of the header in the TCP segment and IP datagram?

The header should have a minimum length of 20 bytes and can have a maximum length of 60 bytes.

What is difference between ARP and RARP?

The address resolution protocol (ARP) is used to associate the 32 bit IP address with the 48 bit physical address, used by a host or a router to find the physical address of another host on its network by sending a ARP query packet that includes the IP address of the receiver.
The reverse address resolution protocol (RARP) allows a host to discover its Internet address when it knows only its physical address.

What is ICMP?

ICMP is Internet Control Message Protocol, a network layer protocol of the TCP/IP suite used by hosts and gateways to send notification of datagram problems back to the sender. It uses the echo test / reply to test whether a destination is reachable and responding. It also handles both control and error messages.

What is Bandwidth?

Every line has an upper limit and a lower limit on the frequency of signals it can carry. This limited range is called the bandwidth.

Difference between bit rate and baud rate.

Bit rate is the number of bits transmitted during one second whereas baud rate refers to the number of signal units per second that are required to represent those bits.
Baud rate = bit rate / N
Where N is no-of-bits represented by each signal shift.

What is MAC address ?

The address for a device as it is identified at the Media Access Control (MAC) layer in the network architecture. MAC address is usually stored in ROM on the network adapter card and is unique.

What is attenuation?

The degeneration of a signal over distance on a network cable is called attenuation.

What is cladding?

A layer of a glass surrounding the center fiber of glass inside a fiber-optic cable.

What is RAID?

A method for providing fault tolerance by using multiple hard disk drives.

What is NETBIOS and NETBEUI?

NETBIOS is a programming interface that allows I/O requests to be sent to and received from a remote computer and it hides the networking hardware from applications.
NETBEUI is NetBIOS extended user interface. A transport protocol designed by Microsoft and IBM for the use on small subnets.

What is redirector?

Redirector is software that intercepts file or prints I/O requests and translates them into network requests. This comes under presentation layer.

What is Beaconing?

The process that allows a network to self-repair networks problems. The stations on the network notify the other stations on the ring when they are not receiving the transmissions. Beaconing is used in Token ring and FDDI networks.

What is terminal emulation, in which layer it comes?

Telnet is also called as terminal emulation. It belongs to application layer.

What is frame relay, in which layer it comes?

Frame relay is a packet switching technology. It will operate in the data link layer.

What do you meant by "triple X" in Networks?

The function of PAD (Packet Assembler Disassembler) is described in a document known as X.3. The standard protocol has been defined between the terminal and the PAD, called X.28; another standard protocol exists between hte PAD and the network, called X.29. Together, these three recommendations are often called "triple X".

What is SAP?

Series of interface points that allow other computers to communicate with the other layers of network protocol stack.

What is subnet?

A generic term for section of a large networks usually separated by a bridge or router.

What is subnet mask?

It is a term that makes distinguish between network address and host address in IP address. Subnet mask value 0 defines host partition in IP address and value 1 – 255 defines Network address.

Describe 802.3 standards

IEEE 802 — LAN/MAN

IEEE 802.1- Standards for LAN/MAN bridging and management and remote media access control bridging.

IEEE 802.2 — Standards for Logical Link Control (LLC) standards for connectivity.

IEEE 802.3 — Ethernet Standards for Carrier Sense Multiple Access with Collision Detection (CSMA/CD).

IEEE 802.4 — Standards for token passing bus access.

IEEE 802.5 — Standards for token ring access and for communications between LANs and MANs

IEEE 802.6 — Standards for information exchange between systems.

IEEE 802.7 — Standards for broadband LAN cabling.

IEEE 802.8 — Fiber opticconnection.

IEEE 802.9 — Standards for integrated services, like voice and data.

IEEE 802.10 — Standards for LAN/MAN security implementations.

IEEE 802.11 — Wireless Networking – "WiFi".

IEEE 802.12 — Standards for demand priority access method.

IEEE 802.14 — Standards for cable television broadband communications.

IEEE 802.15.1 — Bluetooth

IEEE 802.15.4 — Wireless Sensor/Control Networks – "ZigBee"

IEEE 802.16 — Wireless Networking – "WiMAX"

What is meshing?

Meshing generically describes how devices are connected together. It is also the part of topology. There are two types of meshed topologies: partial and full.
In a partially meshed environment , every device is not connected to every other device.
In a fully meshed environment, every device is connected to every other device.
Wireless is the good example of meshing. Wan ( internet is also a good example of meshing where a computer have connectivity with all internet network.)

Describe Various Network Type

Local Area Networks Local area networks (LANs) are used to connect networking devices that are in a very close geographic area, such as a floor of a building, a building itself, or a campus environment.

Wide Area Networks Wide area networks (WANs) are used to connect LANs together. Typically, WANs are used when the LANs that must be connected are separated by a large distance.

Metropolitan Area Networks A metropolitan area network (MAN) is a hybrid between a LAN and a WAN.

Content Networks Content networks (CNs) were developed to ease users’ access to Internet resources. Companies deploy basically two types of CNs:
1.Caching downloaded Internet information
2.Distributing Internet traffic loads across multiple servers

Storage Area Networks Storage area networks (SANs) provide a high-speed infrastructure to move data between storage devices and file servers.
Advantage
Performance is fast.
Availability is high because of the redundancy features available.
Distances can span up to 10 kilometers.
Management is easy because of the centralization of data resources.
Overhead is low (uses a thin protocol).
Disadvantage of SANs is their cost.

Intranet An intranet is basically a network that is local to a company. In other words, users from within this company can find all of their resources without having to go outside of the company. An intranet can include LANs, private WANs and MANs,

Extranet An extranet is an extended intranet, where certain internal services are made available to known external users or external business partners at remote locations.

Internet An internet is used when unknown external users need to access internal resources in your network. In other words, your company might have a web site that sells various products, and you want any external user to be able to access this service.

VPN A virtual private network (VPN) is a special type of secured network. A VPN is used to provide a secure connection across a public network, such as an internet. Extranets typically use a VPN to provide a secure connection between a company and its known external users or offices. Authentication is provided to validate the identities of the two peers. Confidentiality provides encryption of the data to keep it private from prying eyes. Integrity is used to ensure that the data sent between the two devices or sites has not been tampered with.

Name of seven layers in Open System Interconnection model.

They are Application, Presentation, Session, Transport, Network, Data link, and Physical.

What is the difference between ARP and RARP?

The address resolution protocol (ARP) is used to associate the 32 bit IP address with the 48 bit physical address, used by a host or a router to find the physical address of another host on its network by sendinga ARP uery packet that includes the IP address of the receiver.
The reverse address resolution protocol (RARP) allows a host to discover its Internet address when it knows only its physical address.

What is Client/Server?

What is MAC address?

It is the 48 bit hardware address of LAN card. MAC address is usually stored in ROM on the network adapter card and it is unique.

What are the perquisites to configure server?

LAN card should be connected:

Root (partition on which window is installed) should in NTFS

Server should be configured with a static IP address

How we will configure ADS?

Start ==> RUN ==> DCPROMO

How will you test LAN card?

Ping 127.0.0.1
If getting reply its fine

What are the difference between DOMAIN and WORKGROUP?

Which command is used to check the IP address of your system?

ipconfig

Which set wizard will run to do peer to peer networking in XP?

Small home and office setup wizard

Which command is used to check the physical connectivity between two computers?

Ping

What is map drive?

A special feature that will map network resource to my computer.

What is Proxy Server?

Which folder contains ADS installed on server?

NTDS

What is the full form of Internet?

International Networking

Which are the bootable files of 98 and XP ?

In windows98 it is command.com
In XP it is NTLDR

In which partition Linux is installed ?.

What is size of SWAP ?

It’s the hard disk space that is used as RAM for fast processing. In window it’s known as virtual memory and could be set as per retirement via this path
My Computer ==> properties ==>advance
In Linux it’s known as SWAP space and generally taken the double size of physical RAM For example if you have 256 (MB) DDR physical ram then swap space would be 512 MB.

What is full form of C.M.O.S ?

Complementary metal oxide semiconductor

How will you check ip address without using network place ?

Start ==> Run ==> Command ==>ipconfig

What is IP?

Internet Protocol (IP) is an unreliable, best effort delivery, connection-less protocol used for transmitting and receiving data between hosts in a TCP/IP network

What is a DNS resource record?

What protocol is used by DNS name servers?

DNS uses UDP for communication between servers. It is a better choice than TCP because of the improved speed a connectionless protocol offers. Of course, transmission reliability suffers with UDP.

What is the difference between interior and exterior neighbor gateways?

Interior gateways connect LANs of one organization, whereas exterior gateways connect the organization to the outside world.

What is the HELLO protocol used for?

The HELLO protocol uses time instead of distance to determine optimal routing. It is an alternative to the Routing Information Protocol.

What are the three type of routing tables and What are the advantages and disadvantages of these?

The three types of routing tables are fixed, dynamic, and fixed central.
A fixed table must be manually modified every time there is a change.
A dynamic table changes its information based on network traffic, reducing the amount of manual maintenance.
A fixed central table lets a manager modify only one table, which is then read by other devices. The fixed central table reduces the need to update each machine's table, as with the fixed table. Usually a dynamic table causes the fewest problems for a network administrator, although the table's contents can change without the administrator being aware of the change.

What is source route?

It is a sequence of IP addresses identifying the route a datagram must follow. A source route may optionally be included in an IP datagram header.

What is RIP (Routing Information Protocol)?

It is a simple protocol used to exchange information between the routers.

What is SLIP (Serial Line Interface Protocol)?

It is a simple protocol used for transmission of IP datagrams across a serial line.

What is Proxy ARP?

It is using a router to answer ARP requests. This will be done when the originating host believes that a destination is local, when in fact is lies beyond router.

What is OSPF?

It is an Internet routing protocol that scales well, can route traffic along multiple paths, and uses knowledge of an Internet's topology to make accurate routing decisions.

What is Kerberos?

What is a Multi-homed Host?

It is a host that has a multiple network interfaces and that requires multiple IP addresses is called as a Multihomed Host.

What is NVT (Network Virtual Terminal)?

It is a set of rules defining a very simple virtual terminal interaction. The NVT is used in the start of a Telnet session.

What is Gateway-to-Gateway protocol?

It is a protocol formerly used to exchange routing information between Internet core routers.

What is BGP (Border Gateway Protocol)?

What is autonomous system?

It is a collection of routers under the control of a single administrative authority and that uses a common Interior Gateway Protocol.

What is EGP (Exterior Gateway Protocol)?

t is the protocol the routers in neighboring autonomous systems use to identify the set of networks that can be reached within or via each autonomous system.

What is IGP (Interior Gateway Protocol)?

It is any routing protocol used within an autonomous system.

What is Mail Gateway?

It is a system that performs a protocol translation between different electronic mail delivery protocols.

What is wide-mouth frog?

Wide-mouth frog is the simplest known key distribution center (KDC) authentication protocol.

What is silly window syndrome?

What is region?

What is multicast routing?

Sending a message to a group is called multicasting, and its routing algorithm is called multicast routing.

What is traffic shaping?

What is packet filter?

Hubs

Networks using a Star topology require a central point for the devices to connect. Originally this device was called a concentrator since it consolidated the cable runs from all network devices. The basic form of concentrator is the hub.

As shown in Figure; the hub is a hardware device that contains multiple, independent ports that match the cable type of the network. Most common hubs interconnect Category 3 or 5 twisted-pair cable with RJ-45 ends, although Coax BNC and Fiber Optic BNC hubs also exist. The hub is considered the least common denominator in device concentrators. Hubs offer an inexpensive option for transporting data between devices, but hubs don't offer any form of intelligence. Hubs can be active or passive.

An active hub strengthens and regenerates the incoming signals before sending the data on to its destination.

Passive hubs do nothing with the signal.

Ethernet Hubs

An Ethernet hub is also called a multiport repeater. A repeater is a device that amplifies a signal as it passes through it, to counteract the effects of attenuation. If, for example, you have a thin Ethernet network with a cable segment longer than the prescribed maximum of 185 meters, you can install a repeater at some point in the segment to strengthen the signals and increase the maximum segment length. This type of repeater only has two BNC connectors, and is rarely seen these days.

8 Port mini Ethernet Hub

The hubs used on UTP Ethernet networks are repeaters as well, but they can have many RJ45 ports instead of just two BNC connectors. When data enters the hub through any of its ports, the hub amplifies the signal and transmits it out through all of the other ports. This enables a star network to have a shared medium, even though each computer has its own separate cable. The hub relays every packet transmitted by any computer on the network to all of the other computers, and also amplifies the signals.

The maximum segment length for a UTP cable on an Ethernet network is 100 meters. A segment is defined as the distance between two communicating computers. However, because the hub also functions as a repeater, each of the cables connecting a computer to a hub port can be up to 100 meters long, allowing a segment length of up to 200 meters when one hub is inserted in the network.

Multistation Access Unit

A Multistation Access Unit (MAU) is a special type of hub used for token ring networks. The word "hub" is used most often in relation to Ethernet networks, and MAU only refers to token ring networks. On the outside, the MAU looks like a hub. It connects to multiple network devices, each with a separate cable.

Unlike a hub that uses a logical bus topology over a physical star, the MAU uses a logical ring topology over a physical star.

When the MAU detects a problem with a connection, the ring will beacon. Because it uses a physical star topology, the MAU can easily detect which port the problem exists on and close the port, or "wrap" it. The MAU does actively regenerate signals as it transmits data around the ring.

Switches

Switches are a special type of hub that offers an additional layer of intelligence to basic, physical-layer repeater hubs. A switch must be able to read the MAC address of each frame it receives. This information allows switches to repeat incoming data frames only to the computer or computers to which a frame is addressed. This speeds up the network and reduces congestion.

Switches operate at both the physical layer and the data link layer of the OSI Model.

Bridges

A bridge is used to join two network segments together, it allows computers on either segment to access resources on the other. They can also be used to divide large networks into smaller segments. Bridges have all the features of repeaters, but can have more nodes, and since the network is divided, there is fewer computers competing for resources on each segment thus improving network performance.

Bridges can also connect networks that run at different speeds, different topologies, or different protocols. But they cannot, join an Ethernet segment with a Token Ring segment, because these use different networking standards. Bridges operate at both the Physical Layer and the MAC sublayer of the Data Link layer. Bridges read the MAC header of each frame to determine on which side of the bridge the destination device is located, the bridge then repeats the transmission to the segment where the device is located.

Routers

Routers Are networking devices used to extend or segment networks by forwarding packets from one logical network to another. Routers are most often used in large internetworks that use the TCP/IP protocol suite and for connecting TCP/IP hosts and local area networks (LANs) to the Internet using dedicated leased lines.

Routers work at the network layer (layer 3) of the Open Systems Interconnection (OSI) reference model for networking to move packets between networks using their logical addresses (which, in the case of TCP/IP, are the IP addresses of destination hosts on the network). Because routers operate at a higher OSI level than bridges do, they have better packet-routing and filtering capabilities and greater processing power, which results in routers costing more than bridges.

Routing tables

Routers contain internal tables of information called routing tables that keep track of all known network addresses and possible paths throughout the internetwork, along with cost of reaching each network. Routers route packets based on the available paths and their costs, thus taking advantage of redundant paths that can exist in a mesh topology network.

Because routers use destination network addresses of packets, they work only if the configured network protocol is a routable protocol such as TCP/IP or IPX/SPX. This is different from bridges, which are protocol independent. The routing tables are the heart of a router; without them, there's no way for the router to know where to send the packets it receives.

Unlike bridges and switches, routers cannot compile routing tables from the information in the data packets they process. This is because the routing table contains more detailed information than is found in a data packet, and also because the router needs the information in the table to process the first packets it receives after being activated. A router can't forward a packet to all possible destinations in the way that a bridge can.

Static routers: These must have their routing tables configured manually with all network addresses and paths in the internetwork.

Dynamic routers: These automatically create their routing tables by listening to network traffic.

Routing tables are the means by which a router selects the fastest or nearest path to the next "hop" on the way to a data packet's final destination. This process is done through the use of routing metrics.

Routing metrics which are the means of determining how much distance or time a packet will require to reach the final destination. Routing metrics are provided in different forms.

hopis simply a router that the packet must travel through.

Ticks measure the time it takes to traverse a link. Each tick is 1/18 of a second. When the router selects a route based on tick and hop metrics, it chooses the one with the lowest number of ticks first.

You can use routers, to segment a large network, and to connect local area segments to a single network backbone that uses a different physical layer and data link layer standard. They can also be used to connect LAN's to a WAN's.

Brouters

Brouters are a combination of router and bridge. This is a special type of equipment used for networks that can be either bridged or routed, based on the protocols being forwarded. Brouters are complex, fairly expensive pieces of equipment and as such are rarely used.

A Brouter transmits two types of traffic at the exact same time: bridged traffic and routed traffic. For bridged traffic, the Brouter handles the traffic the same way a bridge or switch would, forwarding data based on the physical address of the packet. This makes the bridged traffic fairly fast, but slower than if it were sent directly through a bridge because the Brouter has to determine whether the data packet should be bridged or routed.

Gateways

A gateway is a device used to connect networks using different protocols. Gateways operate at the network layer of the OSI model. In order to communicate with a host on another network, an IP host must be configured with a route to the destination network. If a configuration route is not found, the host uses the gateway (default IP router) to transmit the traffic to the destination host. The default t gateway is where the IP sends packets that are destined for remote networks. If no default gateway is specified, communication is limited to the local network. Gateways receive data from a network using one type of protocol stack, removes that protocol stack and repackages it with the protocol stack that the other network can use.

Examples

E-mail gateways-for example, a gateway that receives Simple Mail Transfer Protocol (SMTP) e-mail, translates it into a standard X.400 format, and forwards it to its destination

Gateway Service for NetWare (GSNW), which enables a machine running Microsoft Windows NT Server or Windows Server to be a gateway for Windows clients so that they can access file and print resources on a NetWare server

Gateways between a Systems Network Architecture (SNA) host and computers on a TCP/IP network, such as the one provided by Microsoft SNA Server

A packet assembler/disassembler (PAD) that provides connectivity between a local area network (LAN) and an X.25 packet-switching network

CSU / DSU (Channel Service Unit / Data Service Unit)

A CSU/DSU is a device that combines the functionality of a channel service unit (CSU) and a data service unit (DSU). These devices are used to connect a LAN to a WAN, and they take care of all the translation required to convert a data stream between these two methods of communication.

A DSU provides all the handshaking and error correction required to maintain a connection across a wide area link, similar to a modem. The DSU will accept a serial data stream from a device on the LAN and translate this into a useable data stream for the digital WAN network. It will also take care of converting any inbound data streams from the WAN back to a serial communication.

A CSU is similar to a DSU except it does not have the ability to provide handshaking or error correction. It is strictly an interface between the LAN and the WAN and relies on some other device to provide handshaking and error correction.

NICs (Network Interface Card)

Network Interface Card, or NIC is a hardware card installed in a computer so it can communicate on a network. The network adapter provides one or more ports for the network cable to connect to, and it transmits and receives data onto the network cable.

Wireless Lan card

Every networked computer must also have a network adapter driver, which controls the network adapter. Each network adapter driver is configured to run with a certain type of network adapter.

Network card

Network Interface Adapter Functions
Network interface adapters perform a variety of functions that are crucial to getting data to and from the computer over the network.

These functions are as follows:

Data encapsulation
The network interface adapter and its driver are responsible for building the frame around the data generated by the network layer protocol, in preparation for transmission. The network interface adapter also reads the contents of incoming frames and passes the data to the appropriate network layer protocol.

Signal encoding and decoding
The network interface adapter implements the physical layer encoding scheme that converts the binary data generated by the network layer-now encapsulated in the frame-into electrical voltages, light pulses, or whatever other signal type the network medium uses, and converts received signals to binary data for use by the network layer.

transmission and reception
The primary function of the network interface adapter is to generate and transmit signals of the appropriate type over the network and to receive incoming signals. The nature of the signals depends on the network medium and the data-link layer protocol. On a typical LAN, every computer receives all of the packets transmitted over the network, and the network interface adapter examines the destination address in each packet, to see if it is intended for that computer. If so, the network interface adapter passes the packet to the computer for processing by the next layer in the protocol stack; if not, the network interface adapter discards the packet.

Data buffering
Network interface adapters transmit and receive data one frame at a time, so they have built-in buffers that enable them to store data arriving either from the computer or from the network until a frame is complete and ready for processing.

Serial/parallel conversion
The communication between the computer and the network interface adapter runs in parallel, that is, either 16 or 32 bits at a time, depending on the bus the adapter uses. Network communications, however, are serial (running one bit at a time), so the network interface adapter is responsible for performing the conversion between the two types of transmissions.

Media access control
The network interface adapter also implements the MAC mechanism that the data-link layer protocol uses to regulate access to the network medium. The nature of the MAC mechanism depends on the protocol used.

Network protocols

A networked computer must also have one or more protocol drivers (sometimes called a transport protocol or just a protocol). The protocol driver works between the upper-level network software and the network adapter to package data to be sent on the network.

In most cases, for two computers to communicate on a network, they must use identical protocols. Sometimes, a computer is configured to use multiple protocols. In this case, two computers need only one protocol in common to communicate. For example, a computer running File and Printer Sharing for Microsoft Networks that uses both NetBEUI and TCP/IP can communicate with computers using only NetBEUI or TCP/IP.

ISDN (Integrated Services Digital Network) adapters

Integrated Services Digital Network adapters can be used to send voice, data, audio, or video over standard telephone cabling. ISDN adapters must be connected directly to a digital telephone network. ISDN adapters are not actually modems, since they neither modulate nor demodulate the digital ISDN signal.

Like standard modems, ISDN adapters are available both as internal devices that connect directly to a computer's expansion bus and as external devices that connect to one of a computer's serial or parallel ports. ISDN can provide data throughput rates from 56 Kbps to 1.544 Mbps (using a T1 carrier service).

ISDN hardware requires a NT (network termination) device, which converts network data signals into the signaling protocols used by ISDN. Some times, the NT interface is included, or integrated, with ISDN adapters and ISDN-compatible routers. In other cases, an NT device separate from the adapter or router must be implemented. ISDN works at the physical, data link, network, and transport layers of the OSI Model.

WAPs (Wireless Access Point)

A wireless network adapter card with a transceiver sometimes called an access point, broadcasts and receives signals to and from the surrounding computers and passes back and forth between the wireless computers and the cabled network.

Access points act as wireless hubs to link multiple wireless NICs into a single subnet. Access points also have at least one fixed Ethernet port to allow the wireless network to be bridged to a traditional wired Ethernet network.

Modems

A modem is a device that makes it possible for computers to communicate over telephone lines. The word modem comes from Modulate and Demodulate. Because standard telephone lines use analog signals, and computers digital signals, a sending modem must modulate its digital signals into analog signals. The computers modem on the receiving end must then demodulate the analog signals into digital signals.

Modems can be external, connected to the computers serial port by an RS-232 cable or internal in one of the computers expansion slots. Modems connect to the phone line using standard telephone RJ-11 connectors.

Transceivers (media converters)

Transceiver short for transmitter-receiver, a device that both transmits and receives analog or digital signals. The term is used most frequently to describe the component in local-area networks (LANs) that actually applies signals onto the network wire and detects signals passing through the wire. For many LANs, the transceiver is built into the network interface card (NIC). Some types of networks, however, require an external transceiver.

In Ethernet networks, a transceiver is also called a Medium Access Unit (MAU). Media converters interconnect different cable types twisted pair, fiber, and Thin or thick coax, within an existing network. They are often used to connect newer 100-Mbps, Gigabit Ethernet, or ATM equipment to existing networks, which are generally 10BASE-T, 100BASE-T, or a mixture of both. They can also be used in pairs to insert a fiber segment into copper networks to increase cabling distances and enhance immunity to electromagnetic interference (EMI).

Firewalls

In computing, a firewall is a piece of hardware and/or software which functions in a networked environment to prevent some communications forbidden by the security policy, analogous to the function of firewalls in building construction.

A firewall has the basic task of controlling traffic between different zones of trust. Typical zones of trust include the Internet (a zone with no trust) and an internal network (a zone with high trust). The ultimate goal is to provide controlled connectivity between zones of differing trust levels through the enforcement of a security policy and connectivity model based on the least privilege principle.

There are three basic types of firewalls depending on:

whether the communication is being done between a single node and the network, or between two or more networks

whether the communication is intercepted at the network layer, or at the application layer

whether the communication state is being tracked at the firewall or not

With regard to the scope of filtered communication these firewalls are exist:

Personal firewalls, a software application which normally filters traffic entering or leaving a single computer through the Internet.

Network firewalls, normally running on a dedicated network device or computer positioned on the boundary of two or more networks or DMZs (demilitarized zones). Such a firewall filters all traffic entering or leaving the connected networks.

In reference to the layers where the traffic can be intercepted, three main categories of firewalls exist:

network layer firewalls An example would be iptables.

application layer firewalls An example would be TCP Wrapper.

application firewalls An example would be restricting ftp services through /etc/ftpaccess file

These network-layer and application-layer types of firewall may overlap, even though the personal firewall does not serve a network; indeed, single systems have implemented both together.

There's also the notion of application firewalls which are sometimes used during wide area network (WAN) networking on the world-wide web and govern the system software. An extended description would place them lower than application layer firewalls, indeed at the Operating System layer, and could alternately be called operating system firewalls.

Lastly, depending on whether the firewalls track packet states, two additional categories of firewalls exist:

stateful firewalls

stateless firewalls

Network layer firewalls

Network layer firewalls operate at a (relatively low) level of the TCP/IP protocol stack as IP-packet filters, not allowing packets to pass through the firewall unless they match the rules. The firewall administrator may define the rules; or default built-in rules may apply (as in some inflexible firewall systems).

A more permissive setup could allow any packet to pass the filter as long as it does not match one or more "negative-rules", or "deny rules". Today network firewalls are built into most computer operating system and network appliances.

Modern firewalls can filter traffic based on many packet attributes like source IP address, source port, destination IP address or port, destination service like WWW or FTP. They can filter based on protocols, TTL values, netblock of originator, domain name of the source, and many other attributes.

Application-layer firewalls

Application-layer firewalls work on the application level of the TCP/IP stack (i.e., all browser traffic, or all telnet or ftp traffic), and may intercept all packets traveling to or from an application. They block other packets (usually dropping them without acknowledgement to the sender). In principle, application firewalls can prevent all unwanted outside traffic from reaching protected machines.

By inspecting all packets for improper content, firewalls can even prevent the spread of the likes of viruses. In practice, however, this becomes so complex and so difficult to attempt (given the variety of applications and the diversity of content each may allow in its packet traffic) that comprehensive firewall design does not generally attempt this approach.

Proxies

A proxy device (running either on dedicated hardware or as software on a general-purpose machine) may act as a firewall by responding to input packets (connection requests, for example) in the manner of an application, whilst blocking other packets.

Proxies make tampering with an internal system from the external network more difficult, and misuse of one internal system would not necessarily cause a security breach exploitable from outside the firewall (as long as the application proxy remains intact and properly configured). Conversely, intruders may hijack a publicly-reachable system and use it as a proxy for their own purposes; the proxy then masquerades as that system to other internal machines. While use of internal address spaces enhances security, crackers may still employ methods such as IP spoofing to attempt to pass packets to a target network.

Types of Networks

Local Area Networks

Local area networks (LANs) are used to connect networking devices that are in a very close geographic area, such as a floor of a building, a building itself, or a campus environment.

Wide Area Networks

Wide area networks (WANs) are used to connect LANs together. Typically, WANs are used when the LANs that must be connected are separated by a large distance.

Metropolitan Area Networks

A metropolitan area network (MAN) is a hybrid between a LAN and a WAN.

Storage Area Networks

Storage area networks (SANs) provide a high-speed infrastructure to move data between storage devices and file servers.
Advantage

Performance is fast.

Availability is high because of the redundancy features available.

Distances can span up to 10 kilometers.

Management is easy because of the centralization of data resources.

Overhead is low (uses a thin protocol).

Disadvantage of SANs is their cost.

Content Networks

Content networks (CNs) were developed to ease users’ access to Internet resources.
Companies deploy basically two types of CNs:

caching downloaded Internet information

Distributing Internet traffic loads across multiple servers

Intranet

An intranet is basically a network that is local to a company. In other words, users from within this company can find all of their resources without having to go outside of the company. An intranet can include LANs, private WANs and MANs,

Extranet

An extranet is an extended intranet, where certain internal services are made available to known external users or external business partners at remote locations.

Internet

An internet is used when unknown external users need to access internal resources in your network. In other words, your company might have a web site that sells various products, and you want any external user to be able to access this service.

VPN

A virtual private network (VPN) is a special type of secured network. A VPN is used to provide a secure connection across a public network, such as an internet. Extranets typically use a VPN to provide a secure connection between a company and its known external users or offices.

Authentication is provided to validate the identities of the two peers.

Confidentiality provides encryption of the data to keep it private from prying eyes.

Integrity is used to ensure that the data sent between the two devices or sites has not been tampered with.

Error Message:
I have enable NetBIOS over TCP/IP but ipconfig /all shows NetBIOS over TCP/IP disable.

Description:
For some reasons, you have enabled NetBIOS over TCP/IP on W2K/XP but using ipconfig /all still shows NetBIOS over TCP/IP disable.

Possible Solutions:
The alternative solution will be installing NetBEUI to all computers.

Error Message:
I can't see a computer even I can ping \\computername

Description:
Sometimes, you may be able to ping or net view \\computer, but can't see it in My Network Places.

Possible Solutions:
If this is a case, you may want to check the workgroup or domain, make sure they are in the same group or domain. Also check the computer browser issue. In the most cases, you may be able to use the computer resources if it enable file and printer sharing and logon the same logon.

Error Message:
Loading NetBEUI works but not NetBIOS over TCP/IP

Possible Solutions:
In general, computer browser performance improves with fewer protocols or network cards on a computer. This is one of reasons why NetBEUI is not loaded WinXP by default. If loading NetBEUI make the workgroup to see each but not enabling NetBIOS over TCP/IP, this is not name resolution issue. This is because of some reasons such as a firewall running.

Error Message:
Logon ID works on win9x but not W2K/XP

Description:
You can logon all workstations with different OS such as win9x, w2k and xp. If logon win9x, you can access any network resources; but if you logon w2k/xp, you will get access denied fro accessing any network resources.

Possible Solutions:
have your administrator to re-set your password.

Error Message:
One computer cannot access the Internet

Description:
you have a network with a router connecting to the Internet. All computers except one can't access the Internet. That computer can ping most other computers' IPs except the router's LAN IP.

Possible Solutions:
Check the router settings and make sure MAC Address Control doesn't deny that computer.

Error Message:

* Unable to browse the network". The network is not present or not stated when click MS Windows Network under Entire Network.
* "The service has not been started" when using net view or net send.
* You may not be able to logon.

Possible Solutions:
Problems with workstation service you may need to check workstation service and make sure it is running on the computer.
Control panel ==> administrative tools ==> services ==> workstation ( This service should start)

Error Message:

* You may receive "System error 53 has occurred. The network path was not found" when using net view \\computername from a remote computer.
* The service has not been started when using net share.
* You may receive "\\computername is not accessible. Then network path was not found" when trying to browse the computer from My Network Places.
* You may receive "System error 51 has occurred. The remote computer is not available" when using net use to map the computer drive.

Possible Solutions:
Problems with server service you may need to check server service and make sure it is running on the computer.
Control panel ==> administrative tools ==> services ==> server ( This service should start)

Error Message:
Win9x can't see Win2000/XP

Description:
By default, Win2000/XP disables NetBIOS over TCP/IP (NetBuI) for selected clients. In a peer-to-peer network without WINS, Win9x will be unable to browse, locate, or create file and print share connections to a Windows 2000 computer with NetBIOS disabled.

Possible Solutions:
you must setup the Win2000/XP to uses NetBIOS over TCP/IP to communicate with prior versions of Windows NT and other clients, such as Microsoft Windows 95. Alternatively, you may want to add NetBEUI on all workstations in the peer-to-peer network.

Error Message:
Zone Alarm may disable file sharing

Description:
You setup a peer-to-peer network correctly but no one can see one of the networking computers and the computer can't see others. Later you find that Installing ZA prevents file sharing because Zone Alarm will consider all other machines on the network as entrusted and will not allow them to communicate with the machine ZA is installed on.

Possible Solutions:
Disabling Zone Alarm.
To fix this, in the firewall section "ZONE" tab use the ADD button to specify which Ip's or range of ip's are local, it would also be a good idea to specify which NIC is local on a multi-homed machine. To do that,
Go to Security >>Advance button and select the "local zone contents" tab then click Add and specify which ip or range of ip are local also specify local interface on multi-homed machine.

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Systems Administrator Interview Question & Answer

What is firewall?

What are the types of firewalls?

What is Full form of ADS?

How will you register and activate windows?

Where do we use cross and standard cable?

How many pins do serial ports have?

How will check ip address on 98?

How will you make partition after installing windows?

What is IP?

What is private IP?

What is public IP address?

What’s the benefit of subnetting?

What are the differences between static ip addressing and dynamic ip addressing?

What is APIPA?

What are the LMHOSTS files?

What is DHCP scope?

What is FQDN?

What is the DNS forwarder?

Which command will you use to find out the name of the pc in networks?

How will enable sound service in 2003?

How will enable CD burning service in 2003?

How to change settings in command prompt?

How to start DirectX Diagnostic Tool ?

How to determine whether there is an issue with the DNS configuration of your connection to your ISP?

What do you need to do that your browser will point URL www.example.com to the internal IP address 127.99.11.01?

What can you suggest to enhance testing process on windows OS?

What is FTP?

How will you make XP home the client of server 2003?

Where do you take back up from?

What is router?

How will you configure ADS?

What is ADS?

What if this wizard (ADS) is not running?

How will you add a client to server? / How’s the client join a domain? What are the client configurations?

Does it necessary to use administrator account to configure the client?

ISO stand for?

OSI stand for?

What is full form DHCP and how will you configure it?

Difference between XP home and XP professional ?

Which OSI layer does IP belong?

What is a subnet mask?

How many times computer reboot when server 2000 install?

How will you remove this error “ ntldr missing press any key to reboot the system” ?

Why do we do networking?

What are the benefits of networking?

What is network?

What is networking?

What is topology?

What is difference between physical and logical topology?

How many types of topology are available?

What is Full form of ADS?

How will you register and activate windows?

Where do we use cross and standard cable?

How many pins do serial ports have?

How will check ip address on 98?

How will you make partition after installing windows?

What is IP?

What is private IP?

What is public IP address?

What’s the benefit of subnetting?

What are the differences between static ip addressing and dynamic ip addressing?

What is APIPA?

What are the LMHOSTS files?

What is DHCP scope?

What is FQDN?

What is the DNS forwarder?

Which command will you use to find out the name of the pc in networks?

How will enable sound service in 2003?

How will enable CD burning service in 2003?

What is a DNS resource record?

What protocol is used by DNS name servers?

What is the difference between interior and exterior neighbor gateways?

What is the HELLO protocol used for?

What are the three type of routing tables and What are the advantages and disadvantages of these?

What is source route?

What is RIP (Routing Information Protocol)?

How will you add a client to server? /
How’s the client join a domain?
What are the client configurations?