Upgrading 2012 R2 to 2019 Domain Controller / DFRS / DNS / DHCP

[Samuel_Caunt]

Hi All, Looking for some advice been a while since I have had to do an upgrade of the domain controllers but I just want to get people advice on the plan I have put in place to do this:

Current setup is as follows:

Domain Controller	Operating System	Functional Level	FRS / DFRS	Other Functions	ROLE
DC1	Microsoft Windows Server 2012 (64-bit)	Windows Server 2012 R2	FRS	DNS / DHCP	PDC / RID POOL MANAGER
DC2	Microsoft Windows Server 2012 (64-bit)	Windows Server 2012 R2	FRS	DNS / DHCP
DC3	Microsoft Windows Server 2012 (64-bit)	Windows Server 2012 R2	FRS	DNS / DHCP	SCHEMA MASTER / DOMAIN NAMING MASTER
DC4	Microsoft Windows Server 2012 (64-bit)	Windows Server 2012 R2	FRS	DNS / DHCP	INFRASTRUCTURE MASTER

The aim is to upgrade all servers to 2019 and upgrade their functional level to 2016R2 and also if possible or easier keep the existing IP's and Names. 

Things I need to try and avoid if possible:

- No downtime (or minimal)

- No impact on live services if possible i.e clients etc

- In place upgrading 

So In terms of the high level plan it was as follows:

- Upgrade/Migrate to DFRS on all existing DC's

- Create 4 new servers running 2019 i.e DCNEW1, DCNEW2, DCNEW3, DCNEW4 install Active directory and add as a DC Member

- Migrate the FSMO Roles  to the corresponding new server i.e DC1 > DCNEW1 DC2 > DCNEW2 etc etc

- Migrate DHCP / DNS to an other server

- Demote the old DC's from AD 

- Rename / Re-IP the new DC's to the old DC's name and IP address. (I believe I will need to demote the new DCs i.e DCNEW1 and move the FSMO Roles to another server, rename and re-ip the DC to DC1 give it the same ip address, add it as a DC member and then move the FSMO roles back onto it and then repeat this process for each other DC)

Some questions i have:

Do I really need to upgrade to DFRS 1st ?? or can this be avoided?

In a very high level plan, does this sound about right? or am I overthinking or missing anything. 

Is there a much slicker way to achieve my goal?

In order to move a DHCP server I recall just exporting the DHCP scopes exporting/importing using "netsh dhcp server export C:\dhcp.txt all"

If I want to move DNS is there anything else i need to consider other than installing the DNS Role?

How would anyone else approach this?

Help appreciated!

Thanks

[#2]

The two prerequisites to introducing the first 2019 domain controller are that domain functional level needs to be 2008 or higher and older sysvol FRS replication needs to have been migrated to DFSR
https://techcommunity.microsoft.com/t5/Storage-at-Microsoft/Streamlined-Migration-of-FRS-to-DFSR-SYS...

I'd use dcdiag / repadmin tools to verify health correcting all errors found before starting any operations. Then stand up the new 2019, patch it fully, license it, join existing domain, add active directory domain services, promote it also making it a GC (recommended), transfer FSMO roles over (optional), transfer pdc emulator role (optional), use dcdiag / repadmin tools to again verify health, when all is good you can move on to next one.

[#3]

Just checking if there's any progress or updates?

--please don't forget to upvote and mark answers if the reply is helpful--

[#4]

Thanks @Dave Patrick

In terms of the steps to migrate DHCP / DNS does this look ok aswell?

Regards

Sam 

[#5 · Accepted solution]

DNS is integrated within active directory. DHCP is a separate role. You could accept this one as best response and start a new thread about DHCP server installation / migration.