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I have a Windows 2003 Server. It is a Domain Controller and also has the DHCP Server role on it. The DHCP range is 192.168.10.1 to 192.168.10.254, which is class C.

My Active Directory IP is 192.168.10.7 and my Proxy server IP is 192.168.10.1.

My question is: Can I increase the IP range up to 512 or 1024? I dont want to change my DNS, because there are some applications which are already running on this range.

I have done the following exercise:

  • make a scope
    • start IP :192.168.10.1
    • end IP :192.168.13.254
    • Length : 22
    • Subnet mask : 255.255.252.0

It makes two scopes.

After this, a computer with 192.168.12.1 and 192.168.13.1 is not communicate to 192.168.10.1 and 192.168.11.1.

MDMarra
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salman
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2 Answers2

8

Contrary to common belief, you can't just start a network range anywhere you like.

The IP address 192.168.10.1 with mask 255.255.252.0 falls in the range 192.168.8.0-192.168.11.255.

This is why hosts with 10 or 11 in third octet can see each other, but those with 12 or 13 can't (but 12 & 13 can see each other). (They are actually in the 192.168.12.0 - 192.168.15.255 range).

Any traffic from 12,13 -> 10,11 or visa-versa will be trying to go via your default gateway

USD Matt
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    Good catch. I didn't even bother working out if the range in use was valid or not. I probably should have, given the quality of the question. – MDMarra Nov 09 '12 at 19:29
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    Fortunately 192.168.0.0 would be a valid start for everything up to /16 so it's fairly easy to find the valid starts for a subnet that covers '4 class c's' - 192.168.0-3,4-7,8-11,etc. To salman, just for completeness and to provide an actual solution, I suggest you change the range to 8-11 – USD Matt Nov 09 '12 at 19:43
7

This is really hard to follow, but (from what I can make of your question), you'll need to update the subnet mask to 255.255.252.0 on all of the client computers to correspond with the increased scope size. This means manually changing it on statically configured clients like servers and updating your DHCP options on the DHCP server.

Also, you say "It makes two scopes." - It's still one scope, just with a larger netmask.

MDMarra
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