Re: [chrony-users] hostnames vs. IP address in chrony.conf

[Ed W <lists@xxxxxxxxxxxxxx>]

On 31/10/2012 10:12, Miroslav Lichvar wrote:
> On Tue, Oct 30, 2012 at 10:30:45PM +0000, Tomalak Geret'kal wrote:
> > I feel like we've been over this sufficiently to solve the problem.
> > Chrony could near-trivially poll the resolver when required with
> > such a mechanism being rate limited if you're worried about syscall
> > performance, and the history can remain IP-keyed.
> How exactly would chrony do that? As Unruh pointed out, getaddrinfo()
> doesn't probvide the TTL and calling it before sending every NTP packet
> can easily result in making a DNS query over network for every call
> unless a local caching is running (nscd, dnsmasq). Also, with
> pool.ntp.org the addresses are rotated in the results, I think
> that would be difficult to handle correctly.

Yes, and pool.ntp.org has short TTL

I think this would

a) add a *lot* of DNS queries to your infrastructure
b) mean in many cases randomly rotating DNS servers every few minutes, 
which would destroy the ability for chrony to keep history on the servers

I agree it would be good in certain situations, but seems like it breaks 
more situations than it fixes?

Ed

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