Posted on 1998-11-01
Last Modified: 2010-03-18
What would the netmask be for each of three subnets using a fraction part of a block of ip numbers such as 192.168.10.nnn?
Question by:jude53
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Expert Comment

ID: 1587613

Expert Comment

ID: 1587614
 Oh well, JBurghardt beat me to answering the question ... what he said is exactly right, is the netmask for the situation you describe.

Accepted Solution

schmox earned 100 total points
ID: 1587615 would be a class C network, which means that the first three octets are fixed and the last one is variable.
Yes, indeed, for a class C subnet, the netmask is
A class B network, for example, would have a variable part of two octets, hence a subnet mask of

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Author Comment

ID: 1587616
Thanks to all of you for your attention but,
I understand the netmask for a class c network. What I needed to know is, what would be the netmask for three subnets set up as a portion of the original host and what would their ip addresses be given my first example?

Expert Comment

ID: 1587617
You have only 254 addressed to subnet, If you choose as you subnet mask,  that means, the addresses, and will be the same subnet.


Expert Comment

ID: 1587618
OK, got it now. So you don't want the whole 192.168.10.nnn class C network, but you want to divide it into smaller subnets, right?
First of all, you can divide the last octet to get 2, 6, 14, 30 or 62 subnets. If you need 3 subnets, you'd have to take 6. Your subnet mask would be and you would have 30 hosts per subnet. Specifically, the subnets would be:

subnet address:
hosts: through
broadcast address:
subnet address:
netmask: (same for all subnets)
hosts: through
broadcast address:
and so on...

For more calculations, you need a Java-capable browser and the following URL:

Guess that was the answer...


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