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Networking Interview Questions-1

Networking Interview Questions-1

Networking Interview Questions


1. 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.

2. 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.

3. Explain the function of Transmission Control Block

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

4. 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.

5. 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 tracking purposes 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.

6. 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.

7. Which layer of the 7 layer model provides services to the Application layer over the Session layer connection?

8. 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

9. 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.

10. Which OSI Reference Layer controls application to application communication?

11. BOOTP helps a diskless workstation boot. How does it get a message to the network
looking for its IP address and the location of its operating system boot files ?

BOOTP sends a UDP message with a subnetwork broadcast address and waits for a reply from
a server that gives it the IP address. The same message might contain the
name of the machine that has the boot files on it. If the boot image location is not specified, the
workstation sends another UDP message to query the server.

12. What is a DNS resource record?

A 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.

13. 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.

14. 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.

15. 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.

16. What are the advantages and disadvantages of the three types of routing tables?

The three types of routing tables are fixed, dynamic, and fixed central. The 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

17. What is a characteristic of Store and Forward switches?

They read the entire frame and check CRC before forwarding.

18. 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.

19. What is RIP (Routing Information Protocol)?
It is a simple protocol used to exchange information between the routers.

20. What is SLIP (Serial Line Interface Protocol)?
It is a very simple protocol used for transmission of IP datagrams across a serial line.

21. 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.

22. 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.

23. 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.

24. 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 Multi-homed Host.

25. 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.

26. What is Gateway-to-Gateway protocol?

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

27. 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).

28. 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.

29. What is EGP (Exterior Gateway Protocol)

It 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.

30. What is IGP (Interior Gateway Protocol)
It is any routing protocol used within an autonomous system.