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Groups > comp.os.linux.networking > #1486

Re: "Timeout" DNS IP to name resolution

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Chris Davies <chris-usenet@roaima.co.uk> wrote in
news:v1phb9xvie.ln2@news.roaima.co.uk: 

> buck <buck@private.mil> wrote:
>> I run a rather busy Apache web server with HostnameLookups On 
because
>> management wants it so.
> 
> I suspect by your phrasing that this isn't a choice you yourself 
would
> have made. Is there any mileage in offering near real-time
> post-resolution of names? So Aapche would write IP addresses, and
> you'd have something along the lines of this -
> 
>     tail -f access.log |
>      while read IP OTHERSTUFF
>      do
>          NM=`dig +short -x $IP`; echo "${NM:-$IP} $OTHERSTUFF"
>      done > access_with_dns.log
> 
> (Don't use that code; it's only to illustrate the idea.)
> 
> 
>> The problem is IP addresses that don't resolve. [...]
> 
>> 1) What is the difference between immediate return of blank/empty 
set
>> and timeout?

That will work for some reports.
 
> The first is a definitive "there is no information available". But 
you
> can't (shouldn't) draw any definitive conclusions from the second.
> Maybe the network was a little slow today. Maybe your UDP packets or
> the answers got dropped somewhere en route. Maybe the far end's rDNS
> really is misconfigured.

You say "misconfigured".  Does that mean that rDNS is SUPPOSED to be 
set
up?  If so, are you able to cite a reference. 

FWIW and for an example, any ip in the range 124.114.0.0 thru
124.115.255.255 times out so this is not a "busy" situation. 

Thanks for the pseudo code.
--
buck

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Thread

"Timeout" DNS IP to name resolution buck <buck@private.mil> - 2012-06-23 17:56 +0000
  Re: "Timeout" DNS IP to name resolution Chris Davies <chris-usenet@roaima.co.uk> - 2012-06-23 22:29 +0100
    Re: "Timeout" DNS IP to name resolution buck <buck@private.mil> - 2012-06-24 01:05 +0000
      Re: "Timeout" DNS IP to name resolution Pascal Hambourg <boite-a-spam@plouf.fr.eu.org> - 2012-06-24 11:52 +0200
      Re: "Timeout" DNS IP to name resolution Chris Davies <chris-usenet@roaima.co.uk> - 2012-06-24 12:15 +0100
        Re: "Timeout" DNS IP to name resolution Moe Trin <ibuprofin@painkiller.example.tld.invalid> - 2012-06-24 11:09 -0500
          Re: "Timeout" DNS IP to name resolution buck <buck@private.mil> - 2012-06-24 19:50 +0000
            Re: "Timeout" DNS IP to name resolution Moe Trin <ibuprofin@painkiller.example.tld.invalid> - 2012-06-24 19:12 -0500
              Re: "Timeout" DNS IP to name resolution J G Miller <miller@yoyo.ORG> - 2012-06-25 10:22 +0000
  Re: "Timeout" DNS IP to name resolution MJ <me@invalid.org> - 2012-06-27 07:44 +0000
    Re: "Timeout" DNS IP to name resolution buck <buck@private.mil> - 2012-06-29 17:00 +0000
      Re: "Timeout" DNS IP to name resolution Joe Beanfish <joebeanfish@nospam.duh> - 2012-06-29 15:43 -0400
        Re: "Timeout" DNS IP to name resolution buck <buck@private.mil> - 2012-06-30 20:04 +0000
  Re: "Timeout" DNS IP to name resolution Martijn Lievaart <m@rtij.nl.invlalid> - 2012-06-30 00:58 +0200

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