Computer Science - Networking - Discussion

2. 

You are working with a network that is 172.16.0.0 and would like to support 600 hosts per subnet. What subnet mask should you use?

[A]. 255.255.192.0
[B]. 255.255.224.0
[C]. 255.255.240.0
[D]. 255.255.248.0
[E]. 255.255.252.0

Answer: Option E

Explanation:

No answer description available for this question.

Mahesh said: (Apr 14, 2011)  
Ans: Its a class B IP.
No. of host= 2^n-1=600 (where n=numbers of zeros)
So, 2^n=601. Approx. n=10

the subnet mask will be:
11111111.11111111.11111100.00000000 (255.255.252.0)

Harsha said: (Mar 8, 2013)  
No. of hosts=2^n-2.

So, 2^n=602, Approx. n=10.

The subnet mask will be:
11111111.11111111.11111100.00000000 (255.255.252.0).

Rohit Singh said: (Oct 7, 2016)  
Total 16 bits available for representing subnets and hosts since Class B address has 2 octets available.
No. of hosts = 600.
No. of bits needed to represent 600 hosts = round( log(600) to the base (2) ) = 10.
Hence, no. of bits available to represent subnets = 16 - 10 = 6.
From the right end, first host bits are taken then subnet bits.
The subnet mask is when all subnet bits are set to 1 and remaining host bits are set to 0 (in the available octets).

Hence, subnet mask = 11111100.00000000 = 252.0 (Remaining portion will remain the same, i.e., 255.255).

Final mask = 255.255.252.0.

Shruti said: (Dec 13, 2016)  
Thanks @Rohit Singh.

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