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Number of usable addresses on a subnet

I was working through a Cisco book and came across a question asking how many usable addresses there are in a class C subnet.

I answered 256, minus one for the network address and minus one for the broadcast address, i.e. a total of 254.

The book gave the correct answer as 253, but no explanation of why.

I wondered if they were assuming one further address would be used for the default gateway in any subnet, but I would tend to view the router as just another host eligible to receive a host address.

What have I missed?

Reply to
Andrew W Young
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Look at

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where it says that that a class C network can have 254 hosts.

Your explanation about why they say 253 in the book is probably right. There might have been something in the phrasing of the question that implied that there would have to be a router involved which would need one IP address leaving only 253 for "hosts" presumably defined as being some class of non-networking devices like PCs and such.

Cisco da Gama

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Reply to
ciscodagama

if so then you would be right. If the ans was 253, it should've said that something like a router connets 2 Class C networks. So each network has one router. How many addresses for 'PCs' on one of them.

If the book has an error it's good to have it recorded, maybe others have it or will google the problem, so it'll be helpful to them.. what book, what edition, what page?

minor point- you mean Class C network not Class C subnet.

Reply to
q_q_anonymous

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