UGC NET CSE | June 2012 | Part 2 | Question: 14

Question

Which of the following TCP/IP Internet protocol does diskless machine uses to obtain its IP address from a server?

• A. RAP
• B. RIP
• C. ARP
• D. X.25

Answer 1

RARP- obtain IP address from given MAC address

ARP- gives MAC address for given IP address

RIP- used in distance vector routing

X.25-  an ITU-T standard protocol suite for packet switched wide area network (WAN) communication.

Comments

But what is RAP? :O

Answer 2

Answer : ARP

RAP : Short for Route Access Protocol, RAP is a protocol that utilizes port 38 and is used for distributing routing information at all levels of the Internet. RAP is further defined in RFC 1476.

Reference : RFC 1476.

RIP : Routing Information Protocol (RIP) is a dynamic protocol used to find the best route or path from end-to-end (source to destination) over a network by using a routing metric/hop count algorithm. This algorithm is used to determine the shortest path from the source to destination, which allows the data to be delivered at high speed in the shortest time.

Reference : RIP RFC 1058

ARP : Address Resolution Protocol (ARP) is a protocol for mapping an Internet Protocol address (IP address) to a physical machine address that is recognized in the local network

Reference : ARP

X.25 : X.25 is the name given to a suite of protocols used for packet-switched wide area network communication

Reference : X.25

Comments

The answer is RARP, not ARP.  

"RARP server checks it's configuration files to find IP address and send it to the workstation asking for it. "

The protocols are explained in Tanenbaum's Computer Networks book.
Option A. which seems to be a typo.

Answer 3

i don't think it's RAP it must be a typo in printing  it should be RARP

Reverse ARP (or RARP), is used by diskless clients to find their IP addresses given their Ethernet addresses.

Answer 4

Ans: None of the above

Its answer should be RARP

RARP: RARP (Reverse Address Resolution Protocol) is a protocol by which a physical machine in a local area network can request to learn its IP address from a gateway server's Address Resolution Protocol (ARP) table or cache. A network administrator creates a table in a local area network's gateway router that maps the physical machine (or Media Access Control - MAC address) addresses to corresponding Internet Protocol addresses. When a new machine is set up, its RARP client program requests from the RARP server on the router to be sent its IP address. Assuming that an entry has been set up in the router table, the RARP server will return the IP address to the machine which can store it for future use.

On the other hand, ARP is used to obtain MAC address from the given IP address.

When an incoming packet destined for a host machine on a particular local area network arrives at a gateway, the gateway asks the ARP program to find a physical host or MAC address that matches the IP address. The ARP program looks in the ARP cache and, if it finds the address, provides it so that the packet can be converted to the right packet length and format and sent to the machine.