dividing subnets

December 1, 2009 at 13:44:46
Specs: Windows XP, ?
I have a question about subnetting on one of my assignment. i'm having a lot of problems with it. the question is as followed.

you have been assigned the network address 172.32.0.0 with a subnet of 255.255.0.0 to use on your LAN. you need to divide the network into seven subnets. what subnet mask do you use?

if someone could help me with this question and maybe give me the formula on how to work this out i would be very grateful.

thanks
Matt


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#1
December 1, 2009 at 13:50:51
Perhaps this can be helpful

http://www.ralphb.net/ipsubnet/subn...


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#2
December 1, 2009 at 19:11:58
You need 3 bits for the 7 subnets.
Because 2^3 = 8 (the smalles possible)

subnet-mask
decimal
255.255.0.0

binary
11111111.11111111.00000000.00000000
-----------------------------^
You'll start to add the 3 bits from here

So the new subnet-mask is:
decimal
255.255.255.224.0

in binary
11111111.11111111.[111]00000.00000000

The part 00000.00000000 are the bits for the amount of hosts, possible in each network.
So 2 power 13 (2^13) = 8192 (hosts per subnet)

So the usable subnets are:
11111111.11111111.[000]00000.00000000
11111111.11111111.[001]00000.00000000
11111111.11111111.[010]00000.00000000
11111111.11111111.[011]00000.00000000
11111111.11111111.[100]00000.00000000
11111111.11111111.[101]00000.00000000
11111111.11111111.[110]00000.00000000
11111111.11111111.[111]00000.00000000

The subnets are:
1. Subnet
172.32.0.1 - 172.32.31.255
10101100 . 00100000 . [000]00000 . 00000001 - 10101100 . 00100000 . [000]11111 . 11111111

2. Subnet
172.32.32.1 - 172.32.63.255
10101100 . 00100000 . [001]00000 . 00000001 - 10101100 . 00100000 . [001]11111 . 11111111

3. Subnet
172.32.64.1 - 172.32.95.255
10101100 . 00100000 . [010]00000 . 00000001 - 10101100 . 00100000 . [010]11111 . 11111111

4. Subnet
172.32.96.1 - 172.32.127.255
10101100 . 00100000 . [011]00000 . 00000001 - 10101100 . 00100000 . [011]11111 . 11111111

5. Subnet
172.32.128.1 - 172.32.159.255
10101100 . 00100000 . [100]00000 . 00000001 - 10101100 . 00100000 . [100]11111 . 11111111

6. Subnet
172.32.160.1 - 172.32.191.255
10101100 . 00100000 . [101]00000 . 00000001 - 10101100 . 00100000 . [101]11111 . 11111111

7. Subnet
172.32.192.1 - 172.32.223.255
10101100 . 00100000 . [110]00000 . 00000001 - 10101100 . 00100000 . [110]11111 . 11111111

8. Subnet
172.32.224.1 - 172.32.255.255
10101100 . 00100000 . [111]00000 . 00000001 - 10101100 . 00100000 . [111]11111 . 11111111


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#3
December 3, 2009 at 13:10:03
Thank you so much. your've been very helpfull.

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