Skip to content
Related Articles
Open in App
Not now

Related Articles

Computer Networks Quiz | IP Addressing | Question 10

Improve Article
Save Article
  • Difficulty Level : Easy
  • Last Updated : 17 Jul, 2020
Improve Article
Save Article

An Internet Service Provider(ISP) has the following chunk of CIDR-based IP addresses available with it: The ISP wants to give half of this chunk of addresses to Organization A, and a quarter to Organization B, while retaining the remaining with itself. Which of the following is a valid allocation of addresses to A and B?
(A) and
(B) and
(C) and
(D) and

Answer: (A)

Explanation: Since the routing prefix is 20, the ISP has 2^(32-20) or 2^12 addresses. Out of these 2^12 addresses, half (or 2^11) addresses have to be given to organization A and quarter (2^10) addresses have to be given to organization B. So routing prefix for organization A will be 21. For B, it will be 22. If we see all options given in the question, only options (A) and (B) are left as only these options have the same number of routing prefixes. Now we need to choose from option (A) and (B).
To assign addresses to organization A, ISP needs to take the first 20 bits from and fix the 21st bit as 0 or 1. Similarly, ISP needs to fix 21st and 22nd bits for organization B. If we take a closer look at the options (A) and (B), we can see the 21st and 22nd bits for organization B are considered as 0 in both options. So the 21st bit of organization A must be 1. Now take the first 20 bits from and 21st bit as 1, we get addresses for organization A as

Quiz of this Question
Please comment below if you find anything wrong in the above post

My Personal Notes arrow_drop_up
Related Articles

Start Your Coding Journey Now!