Subnetwork

Hello,

I'm from Holland and soon i will do my CCNA examination. I study very hard for it. Could somebody help me with the next question? I know the answer is C, but could somebody explain why?

what is the subnetnumber of a host with an ip address of

172.16.210.0/22?

A. 172.16.42.0 B. 172.16.107.0 C. 172.16.208.0 D. 172.16.252.0 E. 172.16.254.0

Reply to
ardimulder
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the third byte of the subnet mark is :

128+64+32+16+8+4=252,so subnet-mark is 255.255.252.0

256-252=4

the hosts of this subnet should be from 172.16.208.1-172.16.213.254

the answer is C

Reply to
leeloo.au

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You could also try going to the following site for an explaination

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~TechMann2U~

Reply to
TechMann2U

Write down the address in binary:

172 16 210 0 10101100 00010000 11010010 00000000

then write a /22 mask in binary:

255 255 252 0 11111111 11111111 11111100 00000000

finally, do a logical AND between the two, and you get:

10101100 00010000 11010000 00000000

or, in the usual notation, 172.16.208.0.

If you're going for your CCNA you better learn to do these calculation quite fast.

Reply to
pk

The range is

172.16.208.0/22 - 172.16.211.255/22

172.16.213.255 belongs to 172.16.212.0

Reply to
Micheal Watkins

Hey,

i tried to make a little diagram to help me work out the bits etc while subnetting the least significant octet etc...

i know this aint perfect and there are possibly better diagrams out there, but this seemed to help me a bit..... .....pardon the pun!

regards

Harry

Last Octet

128 64 32 16 8 4 2 1

255 1 1 1 1 1 1 1 1 /32 - 20 = 1

254 1 1 1 1 1 1 1 0 /31 - 21 = 2

252 1 1 1 1 1 1 0 0 /30 - 22 = 4

248 1 1 1 1 1 0 0 0 /29 - 23 = 8

240 1 1 1 1 0 0 0 0 /28 - 24 = 16

224 1 1 1 0 0 0 0 0 /27 - 25 = 32

192 1 1 0 0 0 0 0 0 /26 - 26 = 64

128 1 0 0 0 0 0 0 0 /25 - 27 = 128
Reply to
hmmmmmm

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