If you have an existing idea for 2016 environment, it's pretty easy to upgrade to ad FS 2019.
You can also upgrade to AD First 2019 directly from DFS in Windows Server 2012 or two with a couple
of extra steps.
What makes this possible is a concept introduced in Ad FS 2016, and that's the farm behavior level.
This is a farm wide setting that determines the features that ADF's can use.
You can add newer versions of add chefs to an existing farm of older servers and the farm will continue
to run at the earlier farm behaviour level.
This is called a mixed farm and you can't use new features of ADF s while the farm is in this state.
It runs with the features of the older version.
Once all the new notes have been added to the farm, you delete the ad fs 2016 or 2012 or two nodes
from the ADF's farm, and then you can raise the farm behaviour level to the latest version.
Then you have access to all the newest features in ADF's 2019.
Upgrading the farm behaviour level creates a new ADF's configuration database with a new name that corresponds
to the farm behaviour level.
If you're upgrading to add UFC 2019 or even to add UFC 2016 from DFS in Windows Server 2012 or to you
may need to upgrade the schema inactive directory.
It needs to be at level 85 at a minimum.
You'll need the Windows Server installation media for Server 2016 or 2019, and you need to run a couple
of commands to update the forest and domain schemas.
I have another demo environment configured with the Windows Server 2016 domain controller and a 2016
ADF's server.
There's a network load balancer set up with a virtual IP that represents the ADF's service.
And the Nhlbi just points to a single ADF server.
We're going to add in ADF's 2019 server to the load balancer, make it the primary server in the farm,
then remove the 2016 ADF's server and upgrade the farm behaviour level to ADF's 2019.
So let's do all that next.