GATE CSE 2016 | Set 1 | Question: 24

Question

Which one of the following protocols is NOT used to resolve one form of address to another one?

• A. $\textsf{DNS}$
• B. $\textsf{ARP}$
• C. $\textsf{DHCP}$
• D. $\textsf{RARP}$

Comments

Official answer key was option C i.e., DHCP

Source of following links are from GATE 2019 website or archive in PreExam Previous year Question papers or archive and Previous year Answer Keys or archive. So they are authentic.

GATE 2016 Set 1 Question Paper: https://drive.google.com/file/d/11OOjvNF_zzeeeB2oHAi8R5fndsikrjJi/view or archive

GATE 2016 Set 1 Answer Key: https://drive.google.com/file/d/1mbJkwNpy0GMA1zF-CwPjS9rsO8JoxOn5/view or archive

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In order to assign IP address to a device it must have to save somewhere that this device has been assigned this IP address, For this it must save info about this device, which is the MAC address, isn’t this conversion needed in DHCP?

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https://www.geeksforgeeks.org/computer-networks/dynamic-host-configuration-protocol-dhcp/

Answer 1

A) $\textsf{DNS}$ - host name to IP address
B) $\textsf{ARP}$ - IP to MAC
D) $\textsf{RARP}$ - MAC to IP

So ANSWER is C

Comments

Good Explaination .

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DHCP also converts when MAC to IP in static part for servers and local machines in dynamic part so how they can say answer is C ? Its ambiguous.

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DHCP also converts when MAC to IP in static part for servers and local machines in dynamic part so how they can say answer is C ? Its ambiguous.

Your submission appears to be a duplicate.

Answer 2

Answer is DHCP as given in gate 2016 key too. Because  it assigns an ip address to a host connected to internet. It does not convert any address to another.

Comments

what about bootp ?

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sushmita
but in DHCP table there was a field called mac address. Does this assign mac address after getting ip.

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DHCP first check its static table, if mac address - ip address found, it returns the ip address , if not found , it allocates a new one.

 

so DHCP also maps mac address to ip address, but not straight forward as much as ARP , RARP.

Answer 3

A) DNS - host name to IP address or vice versa
B) ARP - IP to MAC
c) DHCP-MAC to IP
D) RARP - MAC to IP
So answer will be A only  because host name is not an adress as in other options.

 

Comments

Lets wait for key ,Everything will be clear :)

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https://www.youtube.com/watch?v=q3MwN9R0Br4

Lec 34, Computer Networks by Prof.S.Ghosh, Department of Computer Science & Engineering, I.I.T.,Kharagpur

Watch from 3:00 to 6:00 He clearly says.. 
"Names  - This is also some kind of address"..

and also here
http://www.cs.princeton.edu/courses/archive/spr08/cos461/slides/08Mapping.ppt
It is given as an address explicitly..

 

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So, what is the answer here ?

Answer 4

Answer would be C as per my knowledge.

Answer 5

Answer – Option C, DHCP.

DNS, ARP, RARP are all address resolution protocols.

DNS(Domain Name Service) – Resolve Host name to it’s corresponding IP address.

ARP(Address Resolution Protocol) – Resolve IP address to MAC address.

RARP(Reverse Address Resolution Protocol) – Resolve MAC address to IP address.

DHCP(Dynamic Host Configuration Protocol) -- With DHCP, every network must have a DHCP server that is responsible for configuration. When a computer is started, it has a built-in Ethernet or other link layer address embedded in the NIC, but no IP address. Much like ARP, the computer broadcasts a request for an IP address on its network. It does this by using a DHCP DISCOVER packet. This packet must reach the DHCP server. If that server is not directly attached to the network, the router will be configured to receive DHCP broadcasts and relay them to the DHCP server, wherever it is located. When the server receives the request, it allocates a free IP address and sends it to the host in a DHCP OFFER packet (which again may be relayed via the router). To be able to do this work even when hosts do not have IP addresses, the server identifies a host using its Ethernet address (which is carried in the DHCP DISCOVER packet)

Answer 6

All answers except DHCP mentioned here convert one form of address to another. Yes a hostname is also a type of address in this context.

 

DHCP assigns. Doesn't convert. It assigns an address.

Comments

RARP also assigns. It doesn’t convert. DHCP works the same way RARP does except for the fact that RARP doesn’t have any relay agent and is static. DHCP is both static and dynamic. It has a mapping table with the MAC addresses and their corresponding IPs (in the static part of the table, of course). Which means it too converts the MAC address to the corresponding IP address (using the static part of the table) and sends the IP address back to the device who was asking for it (just like RARP or BOOTP). Hence option D should also be wrong that way.