Re: New Subnet Needed

From: Dusko Savatovic (savatovic.removespam_at_hotmail.com)
Date: 01/25/05 

Date: Tue, 25 Jan 2005 14:05:11 +0100

In line

"EMagidson" <EMagidson@discussions.microsoft.com> wrote in message
news:5C8AF5B6-2D8F-4BFA-AA77-558C5C208EFB@microsoft.com...

> Currently we are running a class C (10.0.0.0) with a subnet mask of
> 255.255.255.0/24.

As a matter of fact 10.0.0.0/8 network is class A network.

> This results in total of 256 nodes possible on the network,
> OUCH (NEED MORE IPs NOW). I would like to take this to a class B with
> four
> subnets (10.0.0.0) subnet mask of 255.255.192.0/18.

a) Varying number of bits in a subnet mask in 10.0.0.0/8 network does not
make this network a class B network. Class B network has the address range
between 128.0.0.0 and 191.255.255.255

b) Changing subnet mask from 24 bits to 18 bits does not add new subnets.
You still have one subnet, but with more hosts in it.

> Is it possible for me
> just to change the subnet and leave the IP addressing the same right now?

If you borrow bits from the subnet part and add them to the host part in
your network addres, yes you can extend the host address range. Some
examples:

Network ID: 10.0.0.0/24:
Subnet mask: 255.255.255.0
Host range 10.0.0.1 to 10.0.0.254 (254 hosts)

Network ID: 10.0.0.0/23
Subnet mask: 255.255.254.0
Host range 10.0.0.1 to 10.0.1.254 (510 hosts)

Network ID: 10.0.0.0/18
Subnet mask: 255.255.192.0
Host range: 10.0.0.1 to 10.0.63.254 (16382 hosts)

etc

> Where could I make this change within my DCs?

You could make this change in the TCP/IP properties of your local area
connection properties.

> This configuration is within a Windows 2000 server with AD environment.
> Any
> whitepapers or direction is hugely helpful.

http://en.wikipedia.org/wiki/Classful_network
http://www.microsoft.com/technet

> Thank you,
>
> Eric Magidson, CCNA

Please remove CCNA from your signature, you don't deserve it (yet).
And one last advice. Don't do it on your own. Hire somebody who understands
what (s)he is doing.

Dusko Savatovic

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