NTP
NTP Infrastructure
History: Over the years it has been evolving, changing. We used to use outside NTP servers, from the WWW , then one, and later a second member provided NTP. One via a Stratum-1 server (Antenna getting PPS (Pulse-Per-Second) via two u-blox receivers) the other one as a stratum-2 (chrony). Those 2 members moved on and another member started a new project at his "home lab" to provide NTP stratum-1. We have now setup some NTP servers using chrony and we have the member's project online (GPS PPS NTP/chrony server with a NEO 7M GPS unit on a raspberry Pi.)
Use 10.10.10.123 as your NTP server address.
What is NTP and how did it started?
The Network Time Protocol is a "network" protocol for devices to synch their clocks. See Wiki
How it all started, how does it works, with Dr Julian Onions (University of Nottingham, UK) implementing this after meeting the godfather of Internet time, Dave Mills! Video interview
IP
10.10.10.123 - NTP for the mesh ( Use this one )
NTP stats and status
Here are some stats on the NTP servers:
NTP Server at SN1 (as an example).
Alternatives
There are many NTP servers on the Net, google offers it, some hardware maker such as Ubiquiti, etc..