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Change a DNS Server IP address RRS feed

  • Question

  • Hi there,

    I am currently challenged with decommissioning an existing DNS server which is highly used in the environment. So the idea will be standing up a new Domain Controller (with DNS) and assign to it the old IP address of the decommissioned one.

    However this will create issues during replication as clients and server will be querying the new Server (because it's reachable) but won't be able to resolve anything until the replication has finished.

    So I was thinking, how bad is it to give the new Server a temporary IP address, let it replicate and, once completed, change its IP address to the one I need?

    P.S.: Changing DNS settings on all hosts that use a static assignment or to all DHCP server isn't an option.

    Thank you

    Thursday, December 22, 2016 9:00 AM

All replies

  • Hi Simone,

    >>So I was thinking, how bad is it to give the new Server a temporary IP address, let it replicate and, once completed, change its IP address to the one I need?

    If client has enabled DNS caching, client will not be much influenced before DNS caching expired.

    You could configure new DNS address to be alternate DNS server.

    Best Regards

    John


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    Friday, December 23, 2016 8:25 AM
  • Hello Simone.

    Do you have another DC that is not involved with this change or is the one you are decommissioning the only one you have currently?

    Assuming you are using DHCP to distribute the DNS server IP addresses (DHCP option 6) to the clients and assuming you have some flexibility on timing of this and assuming you currently only have one DC, here is what I would recommend:

    Make a note of your current DHCP lease time: I'll use the example of the default of 8 days

    Add your new DC with a "temporary" IP address to the network. Make sure it is also a global catalog server.

    Add the IP address of the new DC to the DHCP option 6 list as the second entry in the list.

    Shorten your lease time significantly. Maybe down to 1 or two hours.

    Wait at least 4 days (based on 1/2 the original 8 day lease time) for the clients to get the new settings from DHCP.

    Decommission the old DC. Don't forget to transfer your FSMOs before and clean up AD and DNS after decommissioning.

    Change the IP address of the new DC to the IP address of the old one.

    Verify that the associated entries in DNS reflect the IP address change.

    Remove the temporary DNS IP address from the DHCP option 6 list and set your lease time to whatever is appropriate, like the default of 8 days.

    I would strongly recommend a second DC on your network if you only have one.

    Hope that helps!

    Ed

    Monday, December 26, 2016 10:53 PM