DHCP Failover - Changing Main Server

[talksr]

Hi there,

 

We have an old 2012 server I am gradually migrating everying over from to a new 2022 server.

I set up DHCP Failover so that both the old 2012 and new 2022 servers have DHCP running.

 

Can anyone tell me the best practice method to make the 2022 server the main primary DHCP server as eventually, we will decomission the 2012.

 

Currently, if I view the Failover Relationship, the name is old2012server.domain-new2022server.domain.

 

The new 2022 server is already added as a DC to the same domain as the old one and the new server has taken over all FSMO roles.

 

 

Thanks in advance for any advice - assuming this DHCP work would be best done in a holiday as it will be disruptive. I will also make the lease times for clients maybe 5 minutes closer to the time I do this work.

[pablo007]

Yes best to do out of hours or during holiday, ensure that the scopes are fully replicated, log into what will be your main new DHCP server delete the failover, be sure it works then DHCP can be removed from old server, ensure any vlans with helpers are updated.

[mavhc]

Set the dhcp lease length times to very low, Then at the end of the day turn old off and new on

[casa]

Yes best to do out of hours or during holiday, ensure that the scopes are fully replicated, log into what will be your main new DHCP server delete the failover, be sure it works then DHCP can be removed from old server, ensure any vlans with helpers are updated.

 

Wonderfull !! Just deleted an old failover today partner down pre covid days, added server 2022 DC as a failover partner, The Local LA are going to add another iphelper on all the vlans to point to the new partners IP address, but retain the old iphelper address so I can add a future backup DC........Adios Windows server 2012r2.

[talksr]

Thanks for your help. I notice the failover is configured as failover partner rather than hot standby. Would this be ok or would it be better to be hot standby before I shut the old one off?

[casa]

If i can remember it was a new failover on my new server, then i deleted the relationship on the old server.

The only problem ive got is DFRS replication is still crying its eyes out on my new server, even though i gracefully removed the old sever as a domain controller. and transferred all the AD roles over.

[talksr]

If i can remember it was a new failover on my new server, then i deleted the relationship on the old server.

The only problem ive got is DFRS replication is still crying its eyes out on my new server, even though i gracefully removed the old sever as a domain controller. and transferred all the AD roles over.

 

Thank you. I think this might be the first time I have ever done this before. It is not something I ever needed to do. I fully replicated earlier, set the DHCP lease to 5 minutes (a few weeks ago in anticipation).

Turned off the old server. Left it five or so minutes, and the systems lost internet access as expect. Their original ipconfig /all was showing old server IP as lease giver.

Released and renewed and it picked up new address with new server. Perfect, but no internet. I realised I had forgotten to put the new server IP in the DNS section of DHCP. Did that, released and renewed, perfect, everything working nicely.

Client stations moaning they can't find desktop when logging in as the Group Pol is configured to look at old server, but nothing that can't be sorted so my test today was a success. Old server back on for now as I have a ton of systems to put on M365 and the outage this afternoon has given me a backlog. Good to see this will work when the time comes and DHCP redundancy is an excellent feature to have enabled anyway.

 

Only odd thing I noticed was that although I had set a 5 min lease time, systems were showing 20 mins to 1 hr lease time on their ipconfig /all.

[casa]

Glad everything works, it is a massive learning process involving trial, error and research. no wonder I got quoted 3.5k - 4k inc vat of some providers.

All the best Casa