dig Resolver Options (init, defnam and dnsrch)

[Mark_Andrews at isc.org]

> I've been playing around with dig's resolver options. I'm particularly
> interested in dig's 2nd line of output...
> 
>    ;; res options: init recurs defnam dnsrch

	RES_INIT
	RES_RECURSE
	RES_DEFNAMES
	RES_DNSRCH
> 
> 1. What does init mean? I can't find any definition of it. I've read
>     dig(1), hostname(7) and resolver(3) and searched Google.
> 
> My 2nd problem is that, while I understand the defnam and dnsrch flags
> theoretically, it never seems to matter whether they're set or not.
> 
> I thought defnam (+[no]defname) determined whether my domain name,
> markhawkes.com, would be appended to whatever host I queried. Thus...

	dig doesn't use the resolver routines that use these flags.
 
>    $ dig pluto
> 
> ....would actually be...
> 
>    $ dig pluto.markhawkes.com
> 
> Instead, I get a nonexistent domain error...
> 
> $ dig pluto
> 
> ; <<>> DiG 8.2 <<>> pluto
> ;; res options: init recurs defnam dnsrch
> ;; got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 4
> ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
> ;; QUERY SECTION:
> ;;      pluto, type = A, class = IN
> 
> ;; AUTHORITY SECTION:
> ..      2h51m5s IN SOA  a.root-servers.net. nstld.verisign-grs.com. (
>                                  2003102201      ; serial
>                                  30M             ; refresh
>                                  15M             ; retry
>                                  1W              ; expiry
>                                  1D )            ; minimum
> 
> ;; Total query time: 14 msec
> ;; FROM: mercury to SERVER: default -- 192.168.0.1
> ;; WHEN: Thu Oct 23 09:39:07 2003
> ;; MSG SIZE  sent: 23  rcvd: 98
> 
> 
> I have to specify the FQDN to make it work...
> 
> 
> $ dig pluto.markhawkes.com +noauthor +nostats +noaddit
> 
> ; <<>> DiG 8.2 <<>> pluto.markhawkes.com +noauthor +noaddit +nostats
> ;; res options: init recurs defnam dnsrch
> ;; got answer:
> ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 57895
> ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 1
> ;; QUERY SECTION:
> ;;      pluto.markhawkes.com, type = A, class = IN
> 
> ;; ANSWER SECTION:
> pluto.markhawkes.com.   3D IN A         192.168.0.6
> 
> 
> Here's my resolv.conf, just FYI...
> 
>    $ cat /etc/resolv.conf
>    domain markhawkes.com
>    nameserver 192.168.0.1
> 
> Can anyone show a dig example where +[no]defname and +[no]search
> actually make a difference?
> 
> Many thanks,
> Marco
> 
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at isc.org