Duplicate Servers

James Browning jamesb.fe80 at gmail.com
Wed Sep 25 12:55:26 UTC 2019

On Wed, Sep 25, 2019, at 3:22 AM Richard Laager via devel <devel at ntpsec.org>

> At work, I have two NTP servers. They are part of the pool, with both
> IPv4 and IPv6.
> Internally, my systems use my NTP servers (marked with prefer) and the
> pool to provide additional sources. As is typical, ntpd prefers IPv6
> after resolving the hostname.
> From time to time, the pool will serve me my own servers. I think ntpd
> automatically deduplicates the sources if I get the IPv6 address.
> However, if I get one of my own servers back by IPv4 address, I can end
> up with a duplicate source.

If you are feeling picky you could restrict the other ipv4 addresses.

> I'm not sure how harmful this is. Should I care?

AFAIK it is not harmful just odd and narrowing. You probably should not

> If I should care, any suggestions on what I should do? Is using my
> sources plus the pool stupid? If not, maybe we could add some sort of
> "blacklist this IP from the pool" feature, which would cover this
> scenario plus others?

I am working on a thing, (which should be ready 32nd of never) that would
sort of handle this. No, using your sources plus the pool is a good thing.
It promotes synergy while avoiding the formation of an echo chamber. Maybe
restrict ignore or noserve (I think nopeer is defunct) would work instead
of the addition of another knob.
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