How to replace DHCP server from domainA with DHCP from domainB?


  • Hello fellow Administrators,

    We have one remote site with one subnet. There's domainA domain controller and about 100 domainA's client computers in that subnet. We're about to send 100 domainB's client computers there as well.

    There's also domainA's DHCP server running on the same subnet. DHCP scope options include domainA's domain name, gw and domainA's DNS server addresses.

    DomainA and DomainB belongs to separate forests and there's two-way trust between them. DomainA DNS has stubzone for DomainB and DomainB has stubzone for domainA. That's how
    clients can resolve hostnames of other domain.

    All domainA's clients in remote site will be replaced gradually with domainB's client computers, but this can take a long time.

    I want to note, that I cannot create second subnet for domainB at the moment.

    At some point, we need to deploy DHCP server to domainB's member server in the remote site. What are the steps I should take to replace existing domainA's DHCP server with domainB's DHCP server while still allowing clients from domainA and domainB to successfully find domain controller of their own domain and being able to resolve hostnames from both domains?

    • Edited by weedee Sunday, April 06, 2014 3:09 PM
    Saturday, April 05, 2014 6:33 AM


All replies

  • When the devices on your network first request an IP address or reach the end of their leases (or you force them to check their lease is still valid) they will simply broadcast a request for a DHCP server, and will accept an offer from the first DHCP server to reply

    Multiple DHCP servers PT 1: Spanning multiple subnets.

    If you have several VLANs or physical network segments that are separated into different subnets, and you want to provide a DHCP service to devices in all those subnets then there are two ways of doing this.

    1. If the router / layer 3 switch separating them can act as a BOOTP/DHCP relay agent, then you can continue to keep all your DHCP server(s) in one or two central parts of your network and configure your DHCP server(s) to support multiple ranges of addresses. In order to support this, your router or layer 3 switch must support the BOOTP relay agent specification covered in section 4 of RFC 1542.

    2. If your router does not support RFC 1542 BOOTP relay agents, or if some of your network segments are geographically dispersed over slow links, then you will need to place one or more DHCP server in each subnet. This ‘local’ DHCP server will only serve its own local segment’s requirements, and there is no interaction between it and other DHCP servers. If this is what you want then you can simply configure each DHCP server as a standalone server, with the details of the address pool for its own subnet, and not worry about any other DHCP servers on other parts of the network. This is the most basic example of having more than one DHCP server on the same network.

    Sunday, April 06, 2014 7:22 AM
  • Hi Syed,

    I edited my original post to better describe my issue.

    Thank for your reply, but I'm actually looking for a help how to migrate DHCP server from domainA to domainB while still allowing client computers from both domains to find domain controller and resolve hostnames from domains.

    Sunday, April 06, 2014 2:56 PM
  • Hi,

    You can follow the guide:

    DHCP Server Migration Guide

    If the destination server is a windows server 2012 or later, please refer to this blog:

    Step-By-Step: Migration of DHCP from Windows Server 2003 to Windows Server 2012

    DHCP don’t have many interaction with AD, the only thing you should do is authorize it after migration. And I guess the DHCP will be move to a different subnet. Then either IP helper or DHCP relay agent is required. As Syed Khairuddin has referred.

    Hope this helps.

    Tuesday, April 08, 2014 6:28 AM
  • I addition to Daniel you can check these link as well

    the above link demonstrate an easy way to migrate DHCP server

    Tuesday, April 08, 2014 6:44 AM
  • Hi Daniel,

    The source DHCP server is running W2008 and destination server is running W2008R2.

    The process described in thr migration guide seems very straight-forward. However, I still have some concerns which were not addressed by the migration guide:

    - Can I migrate even when source and destination server are in separate domains and forests?

    - Do I need to provide DNS domain name of the domainA as DHCP scope option to enable client computers of domainA to successfully locate domain controller of domainA after DHCP migration? Destination DHCP server will be a member server of domainB.

    • Edited by weedee Tuesday, April 08, 2014 4:05 PM
    Tuesday, April 08, 2014 4:01 PM
  • Hi,

    If source and destination servers are in different domains, the destination server must be able to contact a global catalog server for the forest in which the source domain user accounts are located.

    Quote from:

    DHCP Server Migration: Preparing to Migrate

    Scope option should be migrated, if you want to assign a different you should modify it after migration.

    Hope this helps.

    Wednesday, April 09, 2014 7:22 AM
  • Hi,

    Any updates? Is the issue resolved?

    Monday, April 14, 2014 6:03 AM