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How many hosts can be supported by a subnet with a specific mask?

You are given the network with subnet mask to represent your organisation. If it is decided that 3 bits are going to be "borrowed" for subnetting purposes, how many hosts can each subnet have?

need help on this question dont know how to do it

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migrated from Aug 4 '09 at 14:14

This question came from our site for professional and enthusiast programmers.

marked as duplicate by Kyle Brandt, Kara Marfia Aug 5 '09 at 13:24

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

dave: your questions keep getting moved to Why not post them there to begin with? – John Saunders Aug 4 '09 at 13:47
-1 please don't submit homework problems – David Mackintosh Aug 4 '09 at 17:16

2 ^ 5 - 2 = 30

You have an 8 bit subnett (the last 0 in the subnett mask) 8 -3 = 5

The -2 is to remove the broadcast and subnett mask addresses

The answer is 30

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should that be minus 2? (one for the broadcast and one for the network address?) – Dog Ears Aug 4 '09 at 13:47
so you mean i will have 5 hosts to each subnet – dave s Aug 4 '09 at 13:47
or is the network address 0? So it IS 31 as SHiraz has already said. – Dog Ears Aug 4 '09 at 13:54
Dog Ears was right it should have been -2, have updated – Shiraz Bhaiji Aug 4 '09 at 14:53
@dave: no, the answer is 30. although in practice you might find it's actually 29 as one of those addresses will be needed for the gateway. – Le Comte du Merde-fou Aug 4 '09 at 15:18