The naming conventions of computers has long been a divisive topic and often the security of a network needs to be put up against the manageability of an environment. I have worked in environments where the server names dictated exactly what that server did, and I've worked in networks with weird naming conventions that did nothing else than tickle the SysAdmin's fancy.
As a Penetration Tester I will tell you that there are a number of trivial ways for me to glean what Operating System a computer is.
- Nmap does a very effective job of "guessing" what OS a computer is. Try for yourself
nmap -A <IP ADDRESS>
- The MAC address of a computer can be a giveaway in the example of Mac's
- The services running on a machine can provide you with a good clue as to what OS the system is running (Banner grabbing)
- If you can get a user on that system to navigate to a website with a BeEF hook embedded or other mechanism to enumerate the machine then you'll easily identify the OS running.
Typically speaking, the Operating System itself isn't of too much interest to me. I'm more concerned as to what the patch level is like of a specific machine, what services are running on it that might be vulnerable, etc. I personally don't think that putting the operating system in an A name is a security risk in and of itself and I know plenty of organizations that utilize a similar naming convention.