We decided to build a fresh server for 2018.3.
With that, I had heard/seen a presentation at a recent roundup that went something along the lines of getting the new core completely built up and tested and all that, and then when ready change the DNS entry of the old core to the IP of the new core and the devices should start showing up in the new core console where you can then start deploying the new agent, etc.
Is this the case? I changed the hosts file on a test device running 2017.3 and ran inventory scan and security scan. I haven't seen the device show up in my new core, so I wanted to make sure this was even a real process.