[CentOS] Re: DKIM

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


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.
www.redhat.com.edgekey.net.globalredir.akadns.net   canonical name = 
e86.b.akamaiedge.net.
Name:   e86.b.akamaiedge.net
Address: 64.215.167.112

> 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


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