# Subnetwork

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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

Re: Subnetwork
On Jul 31, 9:04 am, ardimul...@gmail.com wrote:

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

Re: Subnetwork
wrote:

*********************************************************************************************************************

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

~TechMann2U~

Re: Subnetwork
ardimulder@gmail.com wrote:

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.

Re: Subnetwork

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    =3D    1

254    1       1         1          1        1       1        1         =
0       /31     -     21   =3D     2

252    1       1         1          1        1       1        0         =
0       /30      -     22    =3D   4

248    1       1         1          1        1       0        0         =
0       /29      -     23   =3D    8

240    1       1         1          1        0       0         0         =
0       /28     -     24   =3D    16

224    1       1         1          0        0       0         0         =
0       /27     -     25   =3D    32

192    1       1         0          0        0        0        0         =
0       /26     -     26   =3D    64

128    1       0         0          0         0       0        0         =
0       /25      -     27   =3D   128

Re: Subnetwork
The range is

172.16.208.0/22 - 172.16.211.255/22

172.16.213.255 belongs to 172.16.212.0