How to find Subnets and Hosts from given IP

Question

I have been learning subnetting for my exam and I came through this question. enter image description here

but why it this? I first thought: 172.20.0.0 can have 254 subnets and 254 Hosts per each subnet. I obviously was wrong. can you please explain me how to get this?

thanks guys

score 2 · Accepted Answer · answered May 04 '13 at 06:33

2

The netmask 255.255.252.0 has 10 zero bits at the end.
2 ^ 10 = 1024, minus a broadcast and a network address = 1022.

If you're using the classful way of dividing your network, 172.20.* is a B network, with a 16 bit size of the network part. That gives 16-10 = 6 bits to spare, that can be split into 2 ^ 6 = 64 networks.

answered May 04 '13 at 06:33

Joachim Isaksson

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+1: 255.255.252.0 = 11111111 11111111 11111100 00000000 – GolezTrol May 04 '13 at 06:36
now I get it. So Hosts are calculated from netmask and subnets are calculated from network - hosts. right? – doniyor May 04 '13 at 06:45

How to find Subnets and Hosts from given IP

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