Pretty simple noob IP question

[Bagley5777]

Hello!  I have a quick question I'm struggling with because I don't have a subnet mask.  The answer is "b" here.  I think I'm overthinking this.  Can someone tell me a quick way to approach these kinds of questions?  I've been confusing myself.  THANKS!

5. The IT director has asked you to set up 14 separate IP networks that can each have up

 to 400 computers. What IANA private IP range should you select?

a. 10.0.0.0–10.255.255.255

b. 172.16.0.0–172.31.255.255

c. 192.168.0.0–192.168.255.255

d. 169.254.0.0–169.254.255.255

[Flavio Miranda · Accepted solution]

Hi

 The question is confuse. As they are asking for up to 400 hosts, none of those option is a good fit. All of then can give you up to 512 hosts as the mask looks like to be /16.

 If I were to choose, I'd choose b as well.

-If I helped you somehow, please, rate it as useful.-

[Joseph W. Doherty]

We can eliminate answer "D" as it's not private address space.

If we assume we cannot form /23s out of the "C" answer networks, i.e. we're doing classful networking, that would eliminate that answer.

Further if we assume we're doing classful networking, and if we cannot subnet, that also eliminates answer "A".

So, only answer "B" provides 16 class B networks that could be used to provide the necessary 14 networks.

If we're not restricted to pure classful networking, subnetting would also allow answer "A", supernetting would allow answer "C" and classless networking would allow all but answer "D".