I've been having a read of past questions from folks wanting to utilise an NTP health monitor. It's a fascinating subject but I do have a number of knowledge gaps to implement a solution.
I'm running version BIG-IP 11.3. The best I could initially do was to run up health monitor using UDP. As it wasn't specifically for NTP, the health check, and I use the term loosely, sends out it's default string, "default send string." It's not surprising that I don't get a response from the pool member and that the Wireshark sniff labels the packet as malformed!
Some of the interesting stuff I have been reading on DevCentral is about a DNS script that can be modified to look like a NTP query and also about a Perl package which I'm presuming relates to Net::NTP on CPAN. Sadly the link to the DNS article was a 404. As for how to utilise Net::NTP once it's been installed on the F5, that's where I have the gaps.
Any pointers would be appreciated from knowledgeable sources.