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

The point to note here is both ARP, RARP are used when "static assignments of IPs" are done i.e. IP given generally set by Admin.
But DHCP is formed to solve this issue too, so it provides dynamic IP's to host that are requesting a IP(see carefully it is not a conversation of MAC to IP but an assignment i.e a new entry is added in Router table for the Host MAC and IP while in ARP and RARP both MAC and IP were already present they is conversion of IP to MAC and vice-versa (no Assignment)).

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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?

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

Were marks given to all?

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Dynamic Host Configuration Protocol (DHCP) is a network protocol that is used to assign IP addresses and other network configuration parameters to devices on a network. It enables devices such as computers, smartphones, and tablets to communicate with each other and access the internet.

DHCP does not directly convert one form of address to another. Instead, it assigns IP addresses to devices on a network and manages the allocation of IP addresses to ensure that each device on the network has a unique IP address. This process is known as IP address assignment.

When a device connects to a network, it sends a broadcast message requesting an IP address. The DHCP server receives the request and assigns an available IP address to the device. The DHCP server also provides the device with the necessary information for accessing other network resources, such as the default gateway and the DNS server.

In summary, DHCP assigns IP addresses to devices on a network and manages the allocation of IP addresses, but it does not directly convert one form of address to another.

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Dhcp has both dynamic and static databases for every query at first check static mapping if it does not get then assign a random IP here also mapping is done na because we have a static  database present.

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

If that is the case, then RARP should also be wrong answer. 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.

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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.

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

We call DNS as ADDRESS RESOLVER.. itself.. so saying domain names are not an address is wrong..

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Sorry, i meant DNS has address resolving mechanism
See in Operations..
First point itself..
ADDRESS RESOLUTION MECHANISM
https://en.wikipedia.org/wiki/Domain_Name_System

The point I am trying to make is Domain names are addresses too..
I Say i live at XYZ BUilding, ABC STREET, DELHI (similar to DOMAIN NAME)
or i can say my address is 51° 28′ 38″ N (similar to IP address).. 
 

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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.