Interesting article about Facebooks Public NTP using Chrony

Hi All,

An interesting read here about how facebook has chosen chrony for their network:

Its a publicly available time network, and tracing route to their servers revealed one in the same data centre building as me, so I have added it to my list of servers.


time* has leap smearing, so you should not mix it with other non-leap smearing sources, or your server will be confused when the next leap second is coming. And your server will be kicked out of the pool (if you joined before) if it does not honor leap second.


How can we learn which servers use “leap second smearing” and which do not?

If they do not disclose (Google and Facebook does) then you can only wait until next leap second happens (currently not before December 2020) and see if they diverge from UTC.


Some NTP pool stratum 2s use a mixture of smeared and non-smeared sources.
The use of smeared sources can sometimes be detected from the returned Reference ID.