This is a question that both myself and my colleague have been wondering about for some time. When Autodesk Maya (for example) starts up in a network licensing model, it will prompt for the network license server hostname/IP address if it is not already set (or if it is not available). After entering a hostname/IP address, the application will send an ICMP PING request to the resulting address in an attempt to verify that the network license manager is available. If the PING request is dropped, Maya will refuse to accept the address as a valid entry for the network license manager.
Thing is, Maya never uses ICMP PING requests in any other part of its network licensing model. If you manually set the address/hostname (such as in registry or license file), then when launched Maya will attempt to obtain a license using ports 2080 and 27000-27009 only, without first attempting to PING the address provided.
When setting up a new server VM in our office to run the network license manager, it took us a while to realize that Maya was "requiring" PING on the server in order to accept the hostname in its little license setup window, as all of our tests in setting up the license server manually were always successful. Our firewalls were routing 2080/2700X, and Maya was humming sweetly when configured manually. When we finally realized what was going on, we just scratched our heads and laughed. For awhile.
While I can accept a network diagnostic application to use ICMP, it just seems very unusual for such a high level application to be using (what is essentially) a low level mechanism to test for the availability of a service. I would instead expect it to use its designated ports, eg 2080, and send some form of a "are you alive" request directly to the service, so that (lmgrd/adskflex) can respond directly. When browsing the internet, I don't expect every webserver in the world to respond to ICMP PING requests, but I would expect them to respond to HTTP port 80/443 requests if they are operating normally.
It is not so much of a problem for us, as once we figured out what was going on we were able to take it into account in our network configuration. It is just one of those things that rubs me the wrong way. I am curious about what others think about the ICMP PING requirement, from both official and unofficial sources, and am also curious if this requirement will be dropped in later software versions.