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Network 192.168.1.0/27: how many subnet?

Posted on 2009-12-19
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Hi,

1) This is related to network 192.168.1.0/27
- this has 32 block ip address
- 0 32 64 96 ....
- The first subnet: 192.168.1.(1-30)
- The 2nd subnet: 192.168.1.(33-62)
..
...
- So the hosts in every subnet is 30 from 2^5 - 2

2) My questions:i) How many SUBNETS does this network have?, ii) What is the FORMULA to calculate those subnets? ( I remember there is a formula for it but forget now; for example if we want to know how many "hosts" in every subnet; the formula for it is 2^5 - 2 = 30 hosts)

3) Any help for the two questions  above?
4) Thank you

tjie
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Question by:tjie
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by:memo_tnt
memo_tnt earned 200 total points
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hi


hosts range: 192.168.1.1 - 192.168.1.30 per subnet

anyways :: use this link useful for subnets and wildcard calculations

http://www.subnet-calculator.com/

Best Regards
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by:Grenu
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The formula to calculate number of the subnets is the same 2^n-2, where n is the number of borrowed bits.
iI assume that the super network was 192.168.1.0/24 and it was divided into a subnets with prefix on 27 bits. So in this case You have borowed 3 bits - You have 6 new networks (2^3-2=6), that You cen use without any problems.
The first one can be used however You have to remember that this is the subnet zero, co not all devicec can support it, You have to remember, this is why normalny you are not counging this subnet, the last subnet is "broadcast" subnet, sp You can not use it. The "broadcast" subnet is the one which have the same broadkasct address as the super network, which is divided into subnets.
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by:Don Johnston
Don Johnston earned 700 total points
ID: 26087876
>How many SUBNETS does this network have?

8

>What is the FORMULA to calculate those subnets?

The same as used to calculate the number of hosts. Just don't subtract 2.

bits    subnets
1        2
2        4
3        8
4       16
5       32
6       64
7      128
8      256

and so on
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ccie22921 earned 900 total points
ID: 26087897
Okay, so what if the user is taking a test and does not have access to a subnet calc?  

Grenu, the formula is not the same.  WHen you are calculating usable hosts you subtract 2 so that you can define network and broadcast.  There is no need to do this when calculating the number of subnets.  

tjie what you need to know is that the formula to calculate usable host address is 2^3-2 and to calculate the number of subnets is 2^3 only.  In this case you would have eight subnets.  Which you do:  Look below please
192.168.1.0/27
192.168.1.0 is your network 192.168.1.1-30 is your usable host range 192.168.1.31 is your broadcast address
192.168.1.32 is your network 192.168.1.33 -62 is your host range 192.168.1.63 is your broadcast
192.168.1.64 is your network 192.168.65 - 94 is your host range 192.168.1.95 is your broadcast
192.168.1.96 network 192.168.97-126 hosts 192.168.1.127 broadcast
192.168.1.128 network 192.168.129-158 hosts 192.168.1.159 broadcast
192.168.1.160 network 192.168.161-190 hosts 192.168.1.191 broadcast
192.168.1.192 network 192.168.193-222 hosts 192.168.1.223 broadcast
192.168.1.224 network 192.168.225-254 hosts 192.168.1.255 broadcast

Viola, there are your eight subnets.



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by:ccie22921
ID: 26087902
well put Don
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