[erlang-bugs] : inet_res: unpredictable resolution failure ?

Raimo Niskanen raimo+erlang-bugs@REDACTED
Thu May 15 11:09:54 CEST 2008

On Thu, May 15, 2008 at 10:10:02AM +0200, Mickaël Rémond wrote:
> >>If retry immediately the query / connect most of the time succeed.
> >>
> >>I know that this module is not documented, but to my knowledge it is
> >>the only way to do DNS lookup on some specific type of records (mx or
> >>srv records).
> >>
> >>I can provide details if you need to.
> >
> >Yes please!
> What would you need ?

The problem is that I do not know.

> Should I put the resolver in debug mode and do many connects until I  
> reproduce the problem ?

Yes why not, is there a debug mode?

> It happens on live system. Error seems to happens when a lot of  
> different resolution are done at the same time.
> The result is that tcp_connect seems sometime to fail with nxdomain,  

Some investigation on the failed name and type, how long
time the failed lookup took. A debug or trace of
just the failed lookup would of course be interesting.

Narrowing the problem; just doing name lookups as the
live system does - does it fail the same way?

Is there a network problem? Does the failed call
go to an external, DNS server, and is that one
suddenly unreachable or doing strange things.

Does the nxdomain reply origin locally?

Many questions but no good idea how to answer them...

> and the retry one second later works.
> -- 
> Mickaël Rémond
>  http://www.process-one.net/


/ Raimo Niskanen, Erlang/OTP, Ericsson AB

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