An easy cross platform way of determining the correct hostid for your system is to use our license tools.
Once you have extracted the tools you will need to open a command prompt/terminal and run
rlmutil rlmhostid ether
rlmutil rlmhostid -q ether
on the server that will host the licenses (for floating licenses) or the local workstation where the software will be used (for node locked licenses).
This will return a 12 digit hexidecimal value (which is the hostid) that looks like: