Subnet Question

I ran across this question on the Cisco site and I am having issues on this. I always thought you had to have the Network ID in order to subnet. Here is the questions though..

Assuming a subnet mask of 255.255.224.0 Which of the following would be valid host Addresses?

124.78.103.0
125.67.32.0
125.78.160.0
126.78.48.0
176.55.96.0
186.211.100.0

Any clarification would be wonderful. thank you.

David

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Comments

Cessation

I believe it would be any multiple of 32 on the third octet.
Because it is 255.255.224.0 that would match up to the 3rd bit which is 32.
IE 1=128 2=192 (128+64) 3=224 (128+64+32) and so on.
I hope this helps somewhat.

dbfield

Cessation wrote:

I believe it would be any multiple of 32 on the third octet.
Because it is 255.255.224.0 that would match up to the 3rd bit which is 32.
IE 1=128 2=192 (128+64) 3=224 (128+64+32) and so on.
I hope this helps somewhat.

Thank you, I had that thought, but I doubted myself. I appreciate the help.

David

r_durant

I don't mean to make it more confusing, but shouldn't the question have asked what are the valid subnet addresses?

Unless the answers the question is seeking is 124.78.103.0, 126.78.48.0 and 186.211.100.0, which are valid host addresses if the mask is 255.255.224.0. (i think)

125.67.32.0, 125.78.160.0 and 176.55.96.0 are all valid subnet numbers, as indicated by Cessation.

Unless it's me that is totally confused...

Netstudent

r_durant wrote:

I don't mean to make it more confusing, but shouldn't the question have asked what are the valid subnet addresses?

Unless the answers the question is seeking is 124.78.103.0, 126.78.48.0 and 186.211.100.0, which are valid host addresses if the mask is 255.255.224.0. (i think)

125.67.32.0, 125.78.160.0 and 176.55.96.0 are all valid subnet numbers, as indicated by Cessation.

Unless it's me that is totally confused...

You are right Ryan, the question is seeking those answer choices. Those are not multiples of 32 and are host addresses. The question can be considered slightly tricky because all answer choices end with a 0 in the last Octect.

r_durant

Ok, i'm not as tired as i thought then...

dbfield

Thank you everyone for the clarification. I think sometimes I try to read too much into the question.

Cessation

dbfield wrote:

Thank you everyone for the clarification. I think sometimes I try to read too much into the question.

You just about summed up my testing experiances...

Bill Kaster

It's not a bad question, the question was indeed worded a little weird. I hear once you start getting to higher and higher certifications, that the questions can get pretty cryptic. Any CISSPs here want to comment on that? Mike?