Mailscanner and DNS

John Rudd jrudd at
Wed Sep 27 17:40:46 IST 2006

Daniel Maher wrote:
>> -----Original Message-----
>> From: mailscanner-bounces at [mailto:mailscanner-
>> bounces at] On Behalf Of Alex Neuman van der Hans
>> Sent: September 26, 2006 9:37 PM
>> To: MailScanner discussion
>> Subject: Re: Mailscanner and DNS
>> No matter how you're doing it, you should still look into installing
>> local DNS caching.
> To be fair, this isn't a /requirement/, but in a lot of cases it can help speed things up quite a bit.  For example, if you're running your MTA at your office, but your DNS is handled remotely by an upstream ISP, you should really look into a local caching DNS server.
> That said, there are certainly instances when running bind on your mail servers isn't necessary.  For example, in our environment, our mail servers are connected via fibre to the same switch as our DNS servers (also fibre).  The additional 2 or 3 milliseconds that it takes to do a DNS lookup via this method are not significant enough to necessitate the local DNS process.
> As always, "general rules" are general for a reason - YMMV. :)

Yeah, the actual problem is that our mail servers have been hitting the 
campus name servers rather hard, so we added 2 local name servers to the 
same physical network as our mail servers.  But we're still seeing 
queries go out to the campus name servers.

We probably ARE going to add caching name servers to the mail servers at 
some point, but right now I'm more concerned with why the new 
resolv.conf entries aren't being obeyed.  If it's that sendmail only 
looks at resolv.conf at start-up, that makes a lot of sense ... and 
hopefully that will fix it.

Thanks for all of the replies!

More information about the MailScanner mailing list