I have a license server that is used for multiple purposes including serving up ArcMap and Geo-Media licenses.
A second IP was recently added to this server, for use in an unrelated IIS project. We needed to have multiple IIS configurations and therefore needed a second IP with a DNS entry to it.
For example purposes, I'll say that the original IP was 10.10.1.11 (computer name ApplicationServer) and that we added 10.10.1.10 to the box. We then created a DNS entry for 10.10.1.10 and called it AltApplicationServer.
When we did this, we broke both the Geo-Media license server and the ArcMap 10.3 license server. I was able to fix the Geo-media license server easily enough by allowing it to use the new IP.
However, I haven't found a solution to the ArcMap License server. I've tried editing service.txt (the original is still preserved)
SERVER this_host ANY 27000
SERVER this_host INTERNET=10.10.1.10 27000
and I tried
SERVER this_host INTERNET=10.10.1.11 27000
I know that there isn't a conflict between Geo-Media and ArcGIS because they were running in parallel before we added the IP. I also know for fact that they are still using different ports.
When I run lmgrd.exe -c service.txt -z
I get "Failed to open the TCP port number in the license."
I'm guessing that its related to the pairing of IP addresses.