0th subnetting

Apparently, from what I am reading, there is some confusion on this.

Most of the test prep questions that I have seen assume that you exclude all 1's and all 0's

Does anyone know cisco's official stance on the exam? or if it varies, will the questions state as such that it includes or excludes all ones and and zeroes???

Here is a sample question from a non-cisco exam prep

The host 213.115.77.0 was subnetted with a /28 subnet.
How many usable subnets and hosts were created as a result?

A. 2 networks with 62 hosts
b. 6 networks with 30 hosts
C. 16 networks with 16 hosts
D. 62 networks with 2 hosts
E 14 networks with 14 hosts
F 16 networks with 14 hosts

Obviously, depending on the inclusion or exclusion of the 0th subnet, the answer could be E or F

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Comments

theseman

With myself never having taken the CCNA, you might want to double check this with others.

It is assumed that you CAN and should use subnet 0 on the CCNA, unless explicitly instructed to NOT use subnet 0.

Travis

dtlokee

theseman wrote:

With myself never having taken the CCNA, you might want to double check this with others.

It is assumed that you CAN and should use subnet 0 on the CCNA, unless explicitly instructed to NOT use subnet 0.

Travis

Yes that is the assumption (ip subnet-zero is enabled.)

Now if ip subnet-zero is off (no ip subnet-zero) then don't use the first and last ranges (the all zeros and all ones subnets)

bighornsheep

According to Todd Lammle's latest book for 640-821, Cisco's official expectation for CCNA is that subnet-zero is allowed. Unless if there is specific instructions to not use subnet zero (and subnet 1), you assume it can be used.

So, the answer is F (or E if you can't use subnet-zero)

r_durant

I've read in posts on this site that Cisco will state whether you would use subnet zero or not...

I don't think they will just leave you hanging like that anyway, with two possible scenarios and two possible answers...

So you assumptions on the answers would be correct, but I think most people just assume subnet zero...

dtlokee

Any questions about subnetting should be obvious what they want.

It may state that subnet-zero is on or off, the answer choice for one or the other simply wont be there and so on.

If you know subnetting, then you have nothing to worry about with regards to ip subnet-zero

njcowboy

dtlokee wrote:

Any questions about subnetting should be obvious what they want.

It may state that subnet-zero is on or off, the answer choice for one or the other simply wont be there and so on.

If you know subnetting, then you have nothing to worry about with regards to ip subnet-zero

Thanks guys.

Subnetting is not a challenge for me. Thank god.

Now if I could master WAN connections, I would be golden

Time to break out a bottle of Sailor Jerry's rum.

Netstudent

Fifteen men on a dead man's chest
Yo ho ho and a bottle of rum.

Drink and the devil had done for the rest
Yo ho ho and a bottle of rum.

Good luck mate!

ITdude

Do they really have cowboys in New Jersey?

I think maybe someone slipped me some rum.

ditto with what dtlokee said regarding subnet zero.

njcowboy

Netstudent wrote:

Fifteen men on a dead man's chest
Yo ho ho and a bottle of rum.

Drink and the devil had done for the rest
Yo ho ho and a bottle of rum.

Good luck mate!

Did you test out today?

r_durant

I think he has it at 3pm, so he may be intransit...if not there already!!

njcowboy

ITdude wrote:

Do they really have cowboys in New Jersey? I think maybe someone slipped me some rum.

ditto with what dtlokee said regarding subnet zero.

We have cowboys here.
Oldest on-going rodeo in the nation is based in cowtown, NJ in salem county.

I don't consider myself from NJ. I am from the state of Southern NJ

Netstudent

nah I'm still here in my office studying while listening to testout. Leaving at 2, getting some lunch, and headin over.