I would like to thank Dan Furse from Response IT for this little trick bit!

When virtulising a domain controller from Physical to Virtual, it is recommended to segregate it from any other domain controllers on the network in-case replication occurs during the convert. Usually servers will be offsite so you can disable the site to site VPN’s during the conversion, onsite you will need to swap the host to a different unroutable subnet  and assign the virtual host an ip on that network for the management port.

After migration you might find that the server’s DNS and DC functionality has stopped working.

If you have a DC that is:

a)      A FSMO role holder

b)      NOT the only DC in a domain

c)       Booted standalone (ie it can’t contact any other DCs in the domain)

If the FSMO role holder can’t talk to at least one of its inbound replication partners after a reboot, it won’t advertise itself as either a DC or a DNS server. This is a precaution in case the FSMO roles may have been changed on other DCs while this one was down, so it has to do an initial sync to check that it is still the FSMO holder before it allows DNS/DC connections

You will need to add the following Registry Key and Reboot the machine, then it will skip initial replication and boot standalone.

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NTDS\Parameters]

“Repl Perform Initial Synchronizations”=dword:00000000