[CentOS] Re: DKIM

Thu Sep 25 18:53:28 UTC 2008
Les Mikesell <lesmikesell at gmail.com>

John R Pierce wrote:
> Les Mikesell wrote:
>> Mail isn't supposed to be rejected for this, but some places probably 
>> do.  A more correct approach is to have one name with the A record and 
>> the matching ptr and make all of the other names CNAMEs.
> no, no, no!     CNAMES are discouraged as they create additional work 
> for everyone else's DNS servers.  

Is there an RFC to that effect?  I didn't realize DNS lookups were a 
scarce resource.

> the only time its proper to use a 
> CNAME is when you are referencing a host on someone else's network who's 
> addressing and management is beyond your control and you won't get 
> notifications if its changing.

I suppose something like this is overkill, though...

Non-authoritative answer:
www.redhat.com  canonical name = www.redhat.com.edgekey.net.
www.redhat.com.edgekey.net      canonical name = 
www.redhat.com.edgekey.net.globalredir.akadns.net   canonical name = 
Name:   e86.b.akamaiedge.net

> for email, all the various domains should have MX records with the mail 
> server's "true" name. 

MX records don't have much to do with the system sending mail.

   Les Mikesell
    lesmikesell at gmail.com