[ntp:questions] Best practice: re-resolve server IP address beforeeach poll/query

Jason Rabel jason at extremeoverclocking.com
Tue Jun 12 23:51:00 UTC 2007

I don't think it should re-resolve before every poll/query, but I think it
would be good if NTP did use and respect DNS refresh/expire info (Actually
the OS's DNS system would handle it, NTP would just make use of querying the
DNS instead of fixing the IP after the initial startup).

If NTP updated IPs according to the DNS info then it would open a whole new
realm of enhancements, especially for the NTP Pool project.

First, stale server entries could automatically be removed instead of
retrying until the end of time (or NTP restarted). A big plus if you ever
needed to change the IP(s) of some NTP servers but didn't have the ability
to notify all the users to restart their clients. For the NTP Pool project
it would allow people to use dynamic DNS services for their NTP servers, and
also allow the pool to more efficiently load balance contributors. Yes you
wouldn't exactly have the ultra long-term stability if you end up changing
all your servers out every few days, but for pool users I think it is still
acceptable. Also if for some reason for pool users you are unable to contact
a server or it is way out of whack the 'refresh' with new servers would fix


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