Changing the IP of A DC.

Thanks for the fast reply.


If I run ipconfig /flushdns wont the clear the DNS cache? ipconfig /registerdns will then register the new DNS.

with DHCP if I just amend scope and router address.

That should be OK right?

in a Domain infrastructure, the DHCP DNS should be your domain controllers. (best practice)

Please do not use 8.8.8.8 and 8.8.4.4 as your DNS in your network :) google doesn't know a thing about your internal servers.

So
Client Computer  Gets IP from DHCP and DNS should be the 192.168.0.1 for example, then you want to change it for 192.168.0.254.
you need to tell the client's computers that your new DNS would be 192.168.0.254 instead of 192.168.0.1 and send the traffic to 8.8.8.8 or 8.8.4.4 as "forwarder" and of course, allow port 53 accessible from the internal network to external so this "query forward" will take place.

If you run ipconfig /flushdns It will clear the DNS cache of the computer your run that ... but i won't update the IP on the NICs network wide :)

apologies but you didn't provide an answer to my comment. I'm not going to use Google's DNS servers. Where moving office and the in house IT will be providing the DNS servers.

If I run ipconfig /flushdns wont the clear the DNS cache? ipconfig /registerdns will then register the new DNS.

ipconfig /flushdns => Clear the DNS CACHE on the computers (yes)
Ipconfig /registerdns => Will register the new IP into the DNS  (the way is CLIENT TO SERVER, not SERVER TO CLIENT)

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with the DHCP change, you make sure that "SERVER TO CLIENT" is refreshed.

and if you want a new IP you'd have to run

ipconfig /release
ipconfig /renew

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network-wide on each computer to get the new IP (on DNS)
and what I said related to the Googles DNS is that a lot of people use them internally like crazy.

OK great, thanks for your help

Well, the DNS servers on a domain environment should be the domain controllers and use external IPs DNS (like google) as forwarders.
You shouldn't use internal DNS as forwarders because it will break the flow to internet

Flow using an external DNS as the forwarder

The client computer asks Domain Controller if DC doesn't have the registry ask to external DNSs, get the answers and answers all the way back until the client's computer.

Flow using a DC DNS as the forwarder
The client computer asks Domain Controler if DC doesn't have the registry asked it will forward the query to the other DC or "ask to himself in an infinitive loop" and it won't work :)

"with the DHCP change, you make sure that "SERVER TO CLIENT" is refreshed."

How do I go about doing that? Just go into DNS and delete all the entries?

Do I need to change the IP address in DNS for the server? Or will it do it automatically?

How do I go about doing that? Just go into DNS and delete all the entries?

That's is not an option, you update DNS on the DHCP scope Options, not on the DNSs, the cons of that is that you will lose all connectivity with the network for a little time, (it could be done after hours, so you don't impact anybody), generally on the servers to have "manual" ip you'd need to go one by one updating to the new IP.

What I'd do is just to change the "DNS Settings" on the "Options of the scope" and wait 7 days", to monitor it and see that all will work flawlessly and without interruptions, if you want to do it immediately, you can do the change on the Options of the scope and then remove all entries on the DHCP leased IPs.