Here is what it will happen, during disaster recovery, the data flow will swing from the Prod Servers to the set of servers in DR Data Center, which,
the IP of the DR servers would still remains the same, but only host name change.
Host is not recognized in Dynatrace by IP or hostname. Each installation of OneAgent contains unique host ID. It's assigned to host after oneagent install. This is why if you uninstall agent, or create new host with the same name, ip and reinstall agent there, it will show in DT as new host.
What if the OneAgent isn't installed per se?
What happen is, the host which installed with OneAgent, a snapshot of it would be taken, then compress as an image and transfer to the host in DR Data Center, and then running there.
In this case, would the DR server get recognized as a seperate host in dynatrace dashboard?
If you are rebuilding from whole-of-disk snapshot, then likely the OneAgent would be present on that host, no? So in that case, the host would still have the original OneAgent and identifier when it launches in other DC.
Depends on your disaster recovery process. If it is simply a case where you are selectively synchronizing particular data partitions for direct restoration only, but rebuilding other parts of the OS & operating environment from scratch, then possibly that's excluding the OneAgent original installation and re-installing it from scratch. In that case, a new installation would be treated as a new host.
Sorry, there is no direct answer here. It depends largely on your environment.
Is it possible for you to consider running through your DR process in a non-production environment to test the scenario?
The other consideration is that actually if IP address remains the same, this simplifies things if you have custom device and service definitions, or NAM integration, because they are heavily reliant on IP address based definitions.