With the release of macOS Mojave the command I was using to set the system clocks of our Mac lab systems stopped working. Here is the old command:

ntpdate -bvs time-a.nist.gov

And here are three examples of the new command:

Apple's time server

sudo sntp -sS time.apple.com

Government server in the USA

sudo sntp -sSt 10 time-b.nist.gov

Government server in Canada

sudo sntp -sSt 4 time.nrc.ca

Perhaps it is not a surprise that of the three servers listed above, the Canadian time server is the fastest and therefore the most accurate, but then again I am in Canada. Apple, of course, configures Mac systems out-of-the box to talk to its own server, time.apple.com. The NIST server sometimes times out frequently, even with a 10 second timeout. Perhaps someone here can suggest a better time server.

For reference, here is a link to the NRC’s NTP page which includes information about a subscription service to an authenticated time server:

https://www.nrc-cnrc.gc.ca/eng/services/time/network_time.html

I'm sure there are similar servers in the USA and elsewhere.