have i gone nuts or something?

wedge1988

So, here is a transcender question thats been frazzling me.

Q:

If a workstation on subnet A has an address of 10.0.17.1/20, what possible addresses can the default gateway for Subnet A have?

A:

any IP address between 10.0.16.1 and 10.0.17.254, except 10.0.17.1

Now, im not amazing at subnetting, but shouldnt it be 10.0.16.1 to 10.0.30.254 if the subnet is a /20 (11111111 11111111 11110000 00000000)

exempt 10.0.17.1

Or is this a blonde moment?

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mikej412

wedge1988 wrote: »

Now, im not amazing at subnetting, but shouldnt it be 10.0.16.1 to 10.0.30.254 if the subnet is a /20 (11111111 11111111 11110000 00000000)

exempt 10.0.17.1

If this were a "Cisco Problem" then I'd think your answer is closer

I'd go with the default gateway could be any of the IPs between 10.0.16.1 to 10.0.31.254 -- except that 10.0.17.1 workstation (assuming it doesn't have any other network connections and it's not doing any internet connection sharing stuff). Microsoft doesn't have any silly old "subnet zero" stuff, right?

wedge1988

If this were a "Cisco Problem" then I'd think your answer is closer

That's exactly what i thought! - Glad im not the only one here with that answer. Phew lol.

I think microsoft are just weird with stuff like this, they always have been. And im pretty sure that they can't use the Subnet 0 stuff like you said.

lol. Ill just take my own advice instead of transcenders in future. :P

Devilsbane

Does anyone know a place where Microsoft states it's policy? I know Cisco is clear that you must subtract 2 from the number of hosts but not for the number of subnets. I'm not entirely sure what Microsoft's stance is with this though.

earweed

I think the case with this problem isn't that those are the only addresses available but that it's the only possible answer that falls in the correct range. It seems like a lot of MS questions and answers get twisted like that.
@Devilsbane- I don't think MS has a specific policy on it, at least that I was able to find. I think they go along with the subtract 2 for hosts but not subnets. I tried finding something on this while studying for the 70-642 but couldn't find anything.

MentholMoose

Devilsbane wrote: »

Does anyone know a place where Microsoft states it's policy? I know Cisco is clear that you must subtract 2 from the number of hosts but not for the number of subnets. I'm not entirely sure what Microsoft's stance is with this though.

I don't think they will test on this at all. AFAIK no MS products care about subnet zero, so it is irrelevant. The Trancender question possibly has an error (they might have meant /23), or possibly they are trying to be tricky by providing a subset of the expected correct answer.