Re: Re[2]: [cobalt-users] DNS reverse address lookup, Raq3i

[Larry Smith <lesmith@xxxxxxxxx>]

On Tuesday 29 October 2002 08:14 pm, COMPUTICA wrote:
> I am not sure if "it's needed", but I know it was in the DNS tutorial
> I went through when first setting up DNS services on my RaQ's.  I have
> never run any domains without both MX records....
>
> Maybe someone else can let you know if it's needed to not....
>
> If not....this thread has taught me something today that will save a
> little bit of time down the road.....  :)

If both "domain.com" and "www.domain.com" point to the same IP address then 
_not_ only is it not needed - it is _not_ recommended and really 
sort-of-kinda-almost- upsets admins such as myself who sit and watch a 
message in queue until it "timesout" with the first MX host only to see it 
connect to the exact same host as the second MX (and have to wait on that 
timeout also)....  Really buggers up mail for remote people having two MX 
records pointing to the same place...  Sort of like a voice mail that says 
"dial 0 for help and if that doesn't work dial 0" (why would it work the 
second time if not the first ??)

Basic bottom line:  you need an MX record per domain.

If "www.domain.com" resolves to an IP - then mail can be delivered there 
anyway - since if there is no MX record for the domain portion of an address 
- EG: someone@xxxxxxxxxxxxxx - then the sending server simply trys to "call" 
that hostname directly.

-- 
Larry Smith
SysAd ECSIS.NET
sysad@xxxxxxxxx