# sendmail and the resolver



## ducu_00 (Feb 5, 2009)

I have 2 freebsd systems....but let the commands speak for themselves:



> [root@fbsd6-c:/usr/ports]# uname -a
> FreeBSD fbsd6-c.bdux.dsdis.ro 6.4-RELEASE FreeBSD 6.4-RELEASE #0: Wed Nov 26 11:43:51 UTC 2008     root@dessler.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  i386
> [root@fbsd6-c:/usr/ports]# cat /etc/resolv.conf
> search          bdux.dsdis.ro
> ...





> [root@fbsd71:~/tmp/ducu]# uname -a
> FreeBSD fbsd71.bdux.dsdis.ro 7.1-RELEASE FreeBSD 7.1-RELEASE #0: Thu Jan  1 14:37:25 UTC 2009     root@logan.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  i386
> [root@fbsd71:~/tmp/ducu]# cat /etc/resolv.conf
> search          bdux.dsdis.ro
> ...




The mailers configurations are the default ones (from the base system), the nsswitch.conf file too (^host: files dns). Didn't touch /etc/hosts either.

Let's see the name server conversations:
....for freebsd 6.4:


> 11:55:02.197484 IP 10.32.0.67.58879 > 10.32.0.1.domain:  46405+ AAAA? fbsd6-c.bdux.dsdis.ro. (39)
> 11:55:02.197777 IP 10.32.0.1.domain > 10.32.0.67.58879:  46405* 0/1/0 (83)
> 11:55:02.198303 IP 10.32.0.67.57464 > 10.32.0.1.domain:  46406+ AAAA? fbsd6-c.bdux.dsdis.ro.bdux.dsdis.ro. (53)
> 11:55:02.198397 IP 10.32.0.1.domain > 10.32.0.67.57464:  46406 NXDomain* 0/1/0 (97)
> ...



...and for freebsd 7.1:


> 11:29:26.542430 IP 10.32.0.69.64982 > 10.32.0.1.domain:  51837+ AAAA? fbsd71.bdux.dsdis.ro. (38)
> 11:29:26.542614 IP 10.32.0.1.domain > 10.32.0.69.64982:  51837* 0/1/0 (82)
> 11:29:26.543198 IP 10.32.0.69.59456 > 10.32.0.1.domain:  51838+ AAAA? fbsd71.bdux.dsdis.ro.bdux.dsdis.ro. (52)
> 11:29:26.543318 IP 10.32.0.1.domain > 10.32.0.69.59456:  51838 NXDomain* 0/1/0 (96)
> ...



See the red lines. The same behaviour for 6.3 and 5.5 releases. What is the reason for these queries?

It seems the questionable queries are harmfull, but they aren't in some network configurations where the name server is a M$ one (my situation) which, in the default configuration:
1. does not forward and
2. returns ServFail, not NXDomain, for the single label queries. For more information, see http://www.tomshardware.co.uk/forum/page-197182_36_0.html
In this setup, the mails stay in the queue and the sendmail logs are full of "stat=Deferred: Name server: kvm0.bdux.dsdis.ro.: host name lookup failure". Do I need to say that `host kvm0.bdux.dsdis.ro` returns the right ipv4 address?

Now, I know there are solutions (by the way, WorkAroundBrokenAAAA is _not_ working in this case), but one question still remains: why the single label queries?

Thank you. For reading the long post, in the first place


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