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Migration of DHCP server from one AD Forest to another

    Question

  • We are in the process of migrating users and their PC's from one AD Forest [Forest A] to a new Forest [Forest B], all servers and resources will remain in the original Forest [Forest A]. Currently the DHCP Server [Windows 2008R2] is in Forest A when finished the user migration I want to migrate the DHCP server from Forest A to Forest B. What is the best way to do this?

    Should I create a new Server in Forest B then migrate the settings with the DHCP migration tool to the new server.

    or

    Should I unauthorize the DHCP server in Forest A then migrate the server to Forest B and then authorize it again?

    Wednesday, December 19, 2012 4:39 PM

Answers

  • If your DNS suffixes are well configured, the only problem will be the obsolete DNS records in the domain: As you know, when you migrate computers to the new domain, new DNS records will be created and the old ones will become obsolete. As this is not easy to manage manually, I would recommend proceeding like the following:

    • In the DNS suffixes provided by the DHCP, please put your new forest ones as primary ones and your old forest ones as secondary ones: Like that you will be sure that DNS resolution based on NetBIOS names will be redirected to the new DNS zones of your new forest: This is not true for FQDNs based resolution
    • Enable aging and scavenging to automatically remove obsolete records having a timestamp (static records are not included)

    The migration of the DHCP server is not risky and you can proceed with it out of the working hours. Both options you provided should work.

    Attention! If you are planning that the new DHCP server will have a new IP address to use then note that you need to configure your DHCP relay agents to forward DHCP requests to the new IP address of your DHCP server. However, it will be easier to re-use the old IP address of your old DHCP server.


    This posting is provided "AS IS" with no warranties or guarantees , and confers no rights

    Thursday, December 20, 2012 1:46 PM
  • ok, what is the best way of cleaning up the DNS records?

    It has been well discussed at the below link. Make sure, you select the option for the DNS updates in the below discussion & you are ready to go.

    http://social.technet.microsoft.com/Forums/en-US/winserverMigration/thread/26defd52-d9a6-4d9f-be6d-de9dc29ab100


    Awinish Vishwakarma - MVP

    My Blog: awinish.wordpress.com

    Disclaimer This posting is provided AS-IS with no warranties/guarantees and confers no rights.

    Thursday, December 20, 2012 12:54 PM
    Moderator

All replies

  • We are in the process of migrating users and their PC's from one AD Forest [Forest A] to a new Forest [Forest B], all servers and resources will remain in the original Forest [Forest A]. Currently the DHCP Server [Windows 2008R2] is in Forest A when finished the user migration I want to migrate the DHCP server from Forest A to Forest B. What is the best way to do this?

    Should I create a new Server in Forest B then migrate the settings with the DHCP migration tool to the new server.

    or

    Should I unauthorize the DHCP server in Forest A then migrate the server to Forest B and then authorize it again?


    The second option should work fine.  Just one question - is the DHCP server performing IP address registration for clients into DNS? If so,(and if using AD-Integrated DNS), when you move forests, the DNS records will now end up in the new forest.  You just want to be prepared for name resolution issues.

    BrianY MCT, MCLC

    Wednesday, December 19, 2012 5:24 PM
  • if option B would cause name resolution issues then would option A be better?

    Wednesday, December 19, 2012 5:48 PM
  • Both options can cause names resolution issues if the DHCP server (and/or client) is registering the records into another AD-integrated zone .  The issue is this - if someone is looking to resolve client IP addresses, which namespace is the client record in? And are they querying the right namespace?

    BrianY MCT, MCLC

    Wednesday, December 19, 2012 6:55 PM
  • ok, what is the best way of cleaning up the DNS records?

    Wednesday, December 19, 2012 10:56 PM
  • Instead of taking the backup and restoting the DHCP from one forest to other just install DHCP role on the new forest server and once the clients are online they will register the record in DHCP.If you need to assign specific IP address to some clients you can configure reservation.
    DHCP Server Installation & Configuration:http://www.windowsnetworking.com/articles_tutorials/dhcp_server_windows_2003.html


    Best Regards,

    Sandesh Dubey.

    MCSE|MCSA:Messaging|MCTS|MCITP:Enterprise Adminitrator | My Blog

    Disclaimer: This posting is provided "AS IS" with no warranties or guarantees , and confers no rights.

    Thursday, December 20, 2012 1:39 AM
  • For your information; I faced an issue with DHCP server migration.

    Migration with NETSH-Different language does not support.

    If you need the ip addresses from the remote forest DHCP server ; you need to enable the IPHELPER into the router.

     

    Best regards Biswajit Biswas Disclaimer: This posting is provided "AS IS" with no warranties or guarantees , and confers no rights. MCP 2003,MCSA 2003, MCSA:M 2003, CCNA, MCTS, Enterprise Admin

    Thursday, December 20, 2012 8:14 AM
  • ok, what is the best way of cleaning up the DNS records?

    It has been well discussed at the below link. Make sure, you select the option for the DNS updates in the below discussion & you are ready to go.

    http://social.technet.microsoft.com/Forums/en-US/winserverMigration/thread/26defd52-d9a6-4d9f-be6d-de9dc29ab100


    Awinish Vishwakarma - MVP

    My Blog: awinish.wordpress.com

    Disclaimer This posting is provided AS-IS with no warranties/guarantees and confers no rights.

    Thursday, December 20, 2012 12:54 PM
    Moderator
  • If your DNS suffixes are well configured, the only problem will be the obsolete DNS records in the domain: As you know, when you migrate computers to the new domain, new DNS records will be created and the old ones will become obsolete. As this is not easy to manage manually, I would recommend proceeding like the following:

    • In the DNS suffixes provided by the DHCP, please put your new forest ones as primary ones and your old forest ones as secondary ones: Like that you will be sure that DNS resolution based on NetBIOS names will be redirected to the new DNS zones of your new forest: This is not true for FQDNs based resolution
    • Enable aging and scavenging to automatically remove obsolete records having a timestamp (static records are not included)

    The migration of the DHCP server is not risky and you can proceed with it out of the working hours. Both options you provided should work.

    Attention! If you are planning that the new DHCP server will have a new IP address to use then note that you need to configure your DHCP relay agents to forward DHCP requests to the new IP address of your DHCP server. However, it will be easier to re-use the old IP address of your old DHCP server.


    This posting is provided "AS IS" with no warranties or guarantees , and confers no rights

    Thursday, December 20, 2012 1:46 PM
  • thanks you all for your answers, it has been very helpful.

    Friday, December 21, 2012 11:24 PM