Two domains, two dhcp servers (help with subnet)

15 pts.
DHCP commands
Microsoft Windows Server 2003
Subnet mask
Windows Server 2003 Domain
Hi all, I am having some trouble and I can't get forward... I have two different domains running, both are in the same network. (Scenario is that DC1 is the primary domain of an existing company and DC2 is a new domain for a new company) The DC1 of Domain1 has the ip and the DC2 of Domain2 has the ip Right now both have the subnet Everything is working fine and I they are able to communicate (DNS) also working. What I need is to have two DHCP servers. One on DC1 and one on DC2. DC1 DHCP is giving IPs for company one's clients - DC2 should have two scopes - the first is for and should be considered as a backup if DC1 is gone. The second scope on DC2 should give ip's to the clients of domain two - DHCP won't let me set the two scopes on DC2 as the same subnet - and I don't see any possibility to do what I want without routing. So I need to know what subnet to set and how can I configure WIN SRV 2003 as a router on one of the systems so that they will be able to communicate. I hope you understand me... Thanks for the help.

Software/Hardware used:
Windows Server 2003

Answer Wiki

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Simple problem there my friend – both domains are currently on the same subnet (Network Range). The (/8) you mentioned can be “subnetted” to smaller chunks that will solve the issue you’re having.

From what you’ve posted, a good option is to change your subnet mask to a /24 (

Domain 1 = 10.128.101.x
Domain 2 = 10.129.102.x

Then all you will need is to ensure that you have IP routing set up (if you want the two subnets to be able to communicate with each other.) I know Windows server can be configured to do some simple routing within itself – Good “how-to” from

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  • Encrypt1
    Thank you! Exactly what I did and it seems to be working now.
    15 pointsBadges:
  • Sixball
    Thanks for the Feed-back! :)
    8,705 pointsBadges:
  • Genderhayes
    DHCP works on broadcast traffic; you should only really use multiple DHCP
    servers on the same subnet with a supernet  and the 80/ 20 split require all scopes defined, but the opposite scopes must be disabled.
    10,730 pointsBadges:

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