tell sendmail to use a different dns server?

Luke Kearney lukek at meibin.net
Tue Mar 23 07:11:30 PST 2004


On Tue, 23 Mar 2004 22:30:32 +0800
"Zhang Weiwu" <weiwuzhang at hotmail.com> granted us these pearls of wisdom:

> Zhang Weiwu wrote:
> 
> 
> >> Zhang Weiwu wrote:
> >>
> >
> >>>> Hello. I'm using the dns service on a router box. This router does 
> >
> >>
> >> provide dns service, on which every computer in the LAN has a local
> >> domain name (computername.our.lan)
> >>
> >
> >>>>
> >>>> Now the built in dns server's function is limited; it does not relay 
> MX 
> >
> >>
> >> type of record. Thus sending mail using sendmail always get hostname
> >> lookup failure.
> >>
> >
> >>>> 1. If I change my name server address in resolv.conf to use my ISP's 
> dns 
> >
> >>
> >> server, I cannot access lan computers using local hostnames.
> >>
> >
> >>>> 2. If I use our dns server, I cannot send mails through sendmail.
> >>>>
> >>>> So what should I do? Can I ask sendmail to use ISP's dns server, while 
> 
> >
> >>
> >> the rest programs use local dns server?
> >> I just realized I can do this in resolve.conf:
> >> ====
> >> # our LAN's dns server
> >> nameserver 192.168.0.1
> >> # ISP
> >> nameserver 202.101.103.54
> >>
> >> Hope this is the best method.
> 
> 
> But this works on my notebook but not on my desktop computer, both 5.2
> RELEASE
> 
> dino is my desktop computer:
> dino# cat /etc/resolv.conf
> search realss
> nameserver 192.168.0.138
> nameserver 202.101.103.54
> dino# host -t mx hotmail.com
> Host not found, try again.
> 
> thinkpad is my notebook:
> thinkpad# cat /etc/resolv.conf
> search realss
> nameserver 192.168.0.138
> nameserver 202.101.103.54
> thinkpad# host -t mx hotmail.com
> hotmail.com mail is handled (pri=5) by mx4.hotmail.com
> hotmail.com mail is handled (pri=5) by mx1.hotmail.com
> hotmail.com mail is handled (pri=5) by mx2.hotmail.com
> hotmail.com mail is handled (pri=5) by mx3.hotmail.com

your other option has been to run a split view of your dns so that
internal clients can get an "internal" view being able to resolve each
other and outsiders can only see your external hosts. I believe bind 9.X
can accomplish this. 

HTH

LukeK



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