[time] www.pool.ntp.org down?
Fri Aug 17 21:50:56 UTC 2007
Rob Janssen <rob at knoware.nl> wrote:
> Tim Shoppa wrote:
> > any sane ntp client would either
> > ride these network glitches out or just switch to a reachable server,
> > right?
> As has been discussed, the ntp software we all love (ntpd, previously
> known as xntpd) does not do this.
> When a server is configured with a DNS name (like pool.ntp.org) it
> performs a DNS lookup exactly once at startup of the daemon, and uses
> the IP address to contact the server. When this server fails
> (immediately or later), it does not attempt to do the DNS lookup again,
> so it remains stuck with the same nonfunctional server.
> The risk of this happening can be decreased a bit by using two or three
> servers, but when they all fail there still is a problem.
> Simple-NTP clients often do the lookup for every request so they don't
> show this behaviour.
I was talking about minor network glitches, not a "server gone bad".
When riding out minor network glitches, I don't see how a set of
new glitchily-connected servers is any better than an old set of
glitchily-connected servers. It is extremely likely that the
glitches are following the client rather than the server (or
that they're following a large subset of the servers to only a small
subset of clients), anyway.
Obviously dealing with servers gone bad is not the same thing, but
most servers are up for months or years at a time, right? Don't try
to make it sound like they're things that pop up and go away over a
few hours in common use!
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