[Pool] Valid pool server checks

Harlan Stenn stenn at ntp.org
Wed Apr 1 09:22:55 UTC 2015

If I'm missing something please let me know.

I gather the pool monitors servers and will take a server out of
"rotation" if a problem is found with it.

I'm assuming this includes at least:

- the server has bad time
- the server is advertising improper leap announcements

I think that once a "client" has picked a pool server, it will use that
server until ntpd decides the time offered by that server has "degraded"
relative to other servers.

The problem is that if a server is advertising "bad leap" we won't know
about that until the time service otherwise degrades, or until enough
other servers appear and a proper leap majority is achieved.

There might also be a case where a pool server operator wants to say
"Please tell my clients to go away" without taking their service offline
or otherwise degrading its answers.

So I'm thinking that we might want to add an option to ntpd that would
periodically send a message (do a DNS lookup?) to the pool DNS servers
to ask "Is XXX still a recommended pool server?" and if the answer is
"no" we'd drop that association and spin up a new one.


Harlan Stenn <stenn at ntp.org>
http://networktimefoundation.org  - be a member!

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