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Re: boot ordering and resolvconf



Helmut Grohne wrote:
All that I am aiming for is to declare one of the following practises
as broken:

 * Treating an empty /etc/resolv.conf as a permanent error or failing 
   to discover changes in /etc/resolv.conf later on.
 * Changing /etc/resolv.conf during startup of a local dns cache.


I think that the first one is broken.  If name service is unavailable
just after boot then that should not be treated as a permanent error.

An answer from a nameserver that a domain name does not
exist might more reasonably be treated as a permanent error,
but that is disputable. In a world where computers move among
LANs, DNS does not always look the same, so it's not unreasonable
to retry periodically even after being told NXDOMAIN.

A problem is that getaddrinfo() doesn't distinguish in its return
status between "couldn't reach a nameserver" and "nameserver
says the name doesn't exist".  Either way it returns EAI_SYSTEM
with errno=2 (ENOENT).


> I am not aware that there is anything (except perhaps ntpd) that needs to be fixed.

It is true, that ntpd can work around this issue. Still it appears like
a bad design to treat EAI_SYSTEM as a temporary error.

Can you explain why you think that?
--
Thomas


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