Tim: >> as it's clock via the DHCP daemon (a local server for the LAN). The >> local clock setting is a manual thing left in so NTP carries on running >> if the network is down.
David Woolley: > NTP continues to run regardless of whether or not the network is up, and > regardless of whether there is a local clock configured. There's this little glitch with the current implementation, whether that be NTP or NTP on Fedora: If your internet connection goes down, NTP stops using it to connect to servers. Later, when your internet connection returns, it still makes no attempt to connect to internet servers through the returned connection. So, once outside connection is lost, manual intervention is required to restart the NTP server. I just put a restart script into an ip-up.local script which is run after a PPP connection goes up. But otherwise you end up with a computer no better than if you *never* had NTP on it. > Local clocks should never be used on leaf nodes. I'd debated the wisdom of including a local clock, but it seems without at least one clock that NTP can use, it stops working if it loses network connectivity with other NTP servers. > Also, it is conventional to use a stratum more like 10, to minimise the > damage if anything does try and synch to a machine using a free running > local clock. I'd been advised 9, so that one served as a master (being at least one stratum higher than most individual lost sync clients). So they all stayed together, rather than be able to drift apart as they all sat isolated at stratum 10. > When used as a fallback on servers, local clocks compromise the ability to > estimate the uncertainty in the time, because root dispersion and delay > are reset when the local clock is selected. I'll have to read more on that, because I don't understand the jargon. -- If you insist on e-mailing me, use the reply-to address (it's real but temporary). But please reply to the group, like you're supposed to. This message was sent without a virus, please destroy some files yourself. _______________________________________________ questions mailing list [email protected] https://lists.ntp.isc.org/mailman/listinfo/questions
