Title pretty much explains it. Let's say there's 100 servers, various versions of Windows and Linux, and one Windows server is the "master clock." I did look at this question:

How do I synchronize clocks between Linux and Windows?

This hints that ntp can do what I want if I run "ntpd -q" on a client (?). If I install ntp I also need to guarantee that it will only sync the times when I force it to. Even better if I have a log that tells me every time a sync was performed.

I'm doing benchmark runs and I need to be able to say something like this: "Clocks were synced on all the benchmark systems at 09:42:01am on the master. A benchmark run was then initiated and allowed to run for six hours. None of the system clocks were altered during this time interval."

I understand there is subsequent clock drift, but for now that's the way we're doing things and I'm doing it with a manual process. I'd rather at least automate the one-time sync.