Re: DNS Lookups

["Walden H. Leverich" <WaldenL@xxxxxxxxxxxxxxx>]

>To perform a DNS lookup for an e-mail address, for example user@xxxxxxx
you need to do this:

>a) Look up the A record for "foo.com"
>b) If (A) didn't work, look up the MX records for foo.com
>c) Go through each MX record and look up the corresponding A record.  
>At least one of those MX records needs to resolve to an IP address. 

Why would you ever do step (a)? The existence (or non-existence) of an A
record for techsoftinc.com has no bearing on where our e-mail goes --
and in fact, it doesn't even go to us at all. All our mail goes to
postini for spam/virus filtering and then on to our Exchange SMTP
servers. And the A record for techsoftinc.com points to an entirely
different location than our SMTP servers.

Also, don't forget, it's perfectly valid to have a domain for e-mail
that has no associated A record. Take us.ibm.com as an example.

-Walden

------------
Walden H Leverich III
Tech Software
(516) 627-3800 x3051
WaldenL@xxxxxxxxxxxxxxx
http://www.TechSoftInc.com

Quiquid latine dictum sit altum viditur.
(Whatever is said in Latin seems profound.)