Internal vs. External DNS/Domain Separation Question

[Kevin Darcy]

Justin Piszcz wrote:
> Hello,
>
> I have two domains:
> 1) internal (call it .int)
> 2) external (my domain)
>
> I use bind9 for internal forward/reverse dns and for the external, forward 
> dns only.
>
> When my mail server does dns lookups it looks up not only the domain in 
> question, in this example, RBL checks, but it also appends my 
> internal domain (tries to lookup the address within the scope of my 
> domain):
>
> 14-Sep-2008 05:31:18.745 client 192.168.0.1#52380: query: 98.243.165.206.vote.drbl.balakovo.ru IN A +
> 14-Sep-2008 05:31:18.746 client 192.168.0.1#42269: query: 98.243.165.206.vote.drbl.be.net.ru IN A +
> 14-Sep-2008 05:31:18.747 client 192.168.0.1#40672: query: 98.243.165.206.openlists.orbs.org.int IN A +
> 14-Sep-2008 05:31:18.748 client 192.168.0.1#46048: query: 98.243.165.206.dnsbl.sorbs.net.int IN A +
>
> So there are 2 lookups for every dns lookup (one for domainA and one for 
> domainA.int)..  I have tried utilizing views but that did not seem to fix 
> the problem.  I have tried commenting out the "search int" in all clients &
> servers for /etc/resolv.conf, that did not solve the issue.
>
> Is this normal operation with bind or is there a way to separate this out 
> properly with views, such that:
>
> 1. External DNS lookups only query the actual IP in question and they do 
> not query my local internal domain name?
> 2. Also, I should be able to keep "search int" in /etc/resolv.conf and not 
> have it try to perform external DNS lookups and append the .int?
>   
named is not appending your domain to these queries, the app itself is 
doing so.

Is your MTA by any chance "sendmail"? sendmail uses its own resolver 
routines, so your /etc/resolv.conf settings may have no effect on its 
resolution behavior. Check out sendmail's "ResolverOptions" option; 
setting "-DNSRCH" for that option should probably fix your problem (at 
least, it turns off domain-searching for regular delivery lookups, I'm 
not 100% it'll have any effect on RBL lookups).

If you're running some other MTA, hopefully it has a similar option.

- Kevin