IP-Address

Question 1

An organization requires a range of IP addresses to assign one to each of its 1500 computers. The organization has approached an Internet Service Provider (ISP) for this task. The ISP uses CIDR and serves the requests from the available IP address space 202.61.0.0/17. The ISP wants to assign an address space to the organization which will minimize the number of routing entries in the ISP’s router using route aggregation. Which of the following address spaces are potential candidates from which the ISP can allot any one to the organization?

I. 202.61.84.0/21
II. 202.61.104.0/21 
III. 202.61.64.0/21
IV. 202.61.144.0/21

A	I and II only
B	III and IV only
C	II and III only
D	I and IV only

Computer-NetworksIP-AddressGATE 2020Video-Explanation

Question 1 Explanation:

Given CIDR IP is 202.61.0.0/17 and for HID 32 – 17 = 15 bits can be used.

And to Assign an IP address for 1500 computer, we require 11 bit from HID part.

So NID + SID = 17 + 4 = 21 bits and HID = 11 bits

NID HID
202.61.0 0000 000.00000000

So, from the given option, possible IP Address is

I. 84 -> 0 1010 100 (Because in HID bit 1 is not possible)
II. 104 -> 0 1101 000
III. 64 -> 0 1000 000
IV. 144 -> 1 0010 000 (Because in NID bit 1 is not possible )

Correct Answer: C

Question 1 Explanation:

Given CIDR IP is 202.61.0.0/17 and for HID 32 – 17 = 15 bits can be used.

And to Assign an IP address for 1500 computer, we require 11 bit from HID part.

So NID + SID = 17 + 4 = 21 bits and HID = 11 bits

NID HID
202.61.0 0000 000.00000000

So, from the given option, possible IP Address is

I. 84 -> 0 1010 100 (Because in HID bit 1 is not possible)
II. 104 -> 0 1101 000
III. 64 -> 0 1000 000
IV. 144 -> 1 0010 000 (Because in NID bit 1 is not possible )

Data-Structures

Data-Structures

Data-Structures

Data-Structures

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