Re: [chrony-users] Chrony forgets servers (specified by FQDN) when no DNS server

[Bill Unruh <unruh@xxxxxxxxxxxxxx>]

> Hi Rob, Bill
>
> > On 21/12/2017, at 9:20 AM, Bill Unruh <unruh@xxxxxxxxxxxxxx> wrote:
> >
> > There are two questions here:
> > a) chrony drips a source if the dns does not deliver a valid IP for that
> > server.
> > b)What should the the underlying philosophical stance be of a program like
> > chrony to the use of DNS.
> >
> > I was answering the first, not the second. You had a problem, chronyd was
> > dropping servers if dns failed. My suggestion was how to get around that. You
> > have now expanded this discussion into the second question.
>
> I tend to agree with Rob on this one. I remember a case a few years back where some modem/router vendor had an NTP IP address hardcoded into the device firmware. The owner of the IP ceased providing the NTP service on that address but for years they were still taking a hit from the millions of devices that had been sold. Even though there may have been no NTP server at that address, the packets still had to hit the routers before they were dropped/rejected. If the device vendor had used DNS then their wouldn't have been a problem for the operator of the server.

Certainly having a commercial vendor hard coding the address is really really
horrible, unless it is an address of the vendor's own machines. In that case
the millions of machines the vendor shipped completely swamped the server
(especially since the software used on the vendor's system was incompetently
designed to constantly decrease the time between packets if packet loss
occured.
But that is not what is being discussed here. Here one single person is trying to make his
device more resistant to loosing all of his servers. I have never had much
sympathy with the "What if everyone did it?" argument for behaviour or
morality.

And I do agree that it would be best if his system were robust against loss of
DNS. But as a way around that lack of robustness, "hardcoding" into
/etc/chrony.conf seems a perfectly sensible and acceptable procedure. 
>

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