Subject: Re: How do I get DNS to use TCP instead of UDP?
To: Herb Peyerl <hpeyerl@beer.org>
From: Manuel Bouyer <bouyer@antioche.eu.org>
List: netbsd-help
Date: 08/01/2006 22:46:21
On Tue, Aug 01, 2006 at 02:24:54PM -0600, Herb Peyerl wrote:
> 
> On 1-Aug-06, at 2:21 PM, Manuel Bouyer wrote:
> >>Alternately, is there some proxy that will listen for DNS on
> >>udp and tcp and ship the requests upstream via tcp?
> >
> >Hum, I don't think it's possible at all to do name resolution over  
> >TCP.
> >In nameserver daemons, TCP is only used for synchronisation between
> >servers of the same zone (zone tranfers).
> 
> That was my first thought as well but from resolver(3):
> 
>      RES_USEVC      Use TCP connections for queries instead of UDP  
> datagrams.

Ops. But it seems it's not possible to set it in resolv.conf nor RES_OPTIONS.
dig(8) also mention:
       +[no]tcp
              Use [do not use] TCP when querying name servers. The default
              behaviour is to use UDP unless an AXFR or IXFR query is
              requested, in which case a TCP connection is used.

and this one seems to work.

-- 
Manuel Bouyer <bouyer@antioche.eu.org>
     NetBSD: 26 ans d'experience feront toujours la difference
--