A network with 7 subnets, each with at least 20 hosts, needs to be subnetted. What subnet mask would you pick?
(a) 255.255.254.0
(b) 255.255.254.242
(c) 255.255.255.224
(d) 255.255.255.240
Answer :- (c)
Explanation :-
Remember IP address work on 2’s Power
2^3 means =8
if we use 3 Network bit one then subnet should divide into 8 subnets.
Seven Subnets not possible so we choose Eight Subnet
Required at least 20 Host means
2^5 =32
5 Bits used for Host Portion. 4 bit cannot used because 2^4=16. 4 bit not enough for 20 Hosts
so Correct Subnet Mask Will be
11111111.11111111.11111111.11100000
255.255.255.224 is right subnet for above question
So Correct Answer is (c) Subnet mask will be 255.255.255.224
