Running BIND on a mail server?

[Barry Margolin]

In article <cjp2ds0fqh53alhhta074560u9qd7fd69o at 4ax.com>,
Andrew Fleming  <f236 at scatcat.fhsu.edu> wrote:
>I have just finished making a lot of changes to my named.conf and
>zones, and it has got me thinking about performance.  Two of my mail
>servers have DNS servers running on them, however my other two mail
>servers (which are my main two) do not.  They are using the first two
>servers for DNS lookups.  
>
>Because of spam I have full DNS verification enabled on all of my mail
>servers.  I am thinking about running DNS servers on all of my mail
>servers, because I know that having full DNS verification creates a
>lot of DNS traffic.  That way they would have local cache and cut down
>the time an traffic on the network from this.  Any comments?  
>
>If I installed DNS servers on my main two mail servers, I had thought
>about using the forward option in BIND 8 to have them forward requests
>to my main two DNS servers, so the could take advantage of their cache
>also, and possible cut down some of the DNS traffic on our Internet
>link.  

You're already taking advantage of the main DNS servers' caches by using
them as servers in /etc/resolv.conf.

Running DNS servers on the main mail servers would cut down on the traffic
between the mail servers (because they would use their own caches as well
as the other servers' caches), but wouldn't have much impact on the
Internet link's traffic.

So the questions you need to answer are whether the DNS traffic between the
servers is a problem, and whether you the main mail servers have enough RAM
to support the big DNS caches that will result from running DNS servers.

-- 
Barry Margolin, barmar at bbnplanet.com
GTE Internetworking, Powered by BBN, Burlington, MA
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