NIELIT 2017 DEC Scientific Assistant A - Section B: 28

Question

There is a need to create a network that has $5$ subnets, each with at least $16$ hosts. Which one is used as classful subnet mask ?

• A. $255.255.255.192$
• B. $255.255.255.248$
• C. $255.255.255.240$
• D. $255.255.255.224$

Answer 1

In all the classfull subnet mask option first three octet are same

Difference in last octet:

192 represent in binary : 11000000

 4  subnet  and 62 host

248 represent in binary: 11111000

32 subnet and 6 host

240 represent in binary:  11110000

16 subnets and 14 hosts

224 represent in binary: 11100000

8 subnet and 30 hosts ( most suitable answer)

Option D is correct.

NOTE:

Here we need 5 subnet which is represent in No. Of 1's.

And atleast 16 hosts which is represented of no. Of 0's

Comments

Minor issue, but the question didn’t state whether it’s going to be class $C$ addressing. But that is understood given the masks are $255.255.255.x$