MX Records

[Merton Campbell Crockett]

On 16 Mar 2006, at 12:35 , Kris McElroy wrote:

> This may be the wrong place to ask this, so if it is just let me  
> know and I
> will ask elsewhere.
>
> What is the difference between:
>
> 10 mx0.domain.tld
> 10 mx1.domain.tld


This defines two mail exchange systems.  Sendmail, or whatever, will  
randomize the MX records at each priority for each delivery attempt.   
If delivery fails to the first MX record, it will try the next in the  
list.  If a connection cannot be established to any of the systems,  
delivery will be rescheduled.


> and this:
>
> 10 mx0.domain.tld
>
> mx0.domain   A 192.168.0.1
> 		 A 192.168.0.2


This defines a single mail exchange system with two interfaces.   
Sendmail will "randomly" select one interface for delivery.  If it is  
unable to establish a connection, it will reschedule delivery.  (n.b.  
There may be some versions of sendmail that would try all interfaces  
on each delivery attempt.)


> Which is the better route to go?


That depends on what you are trying to accomplish.  If this is a  
single system and each interface is through a different Internet  
connection, the first is better.  If you don't have two Internet  
connections, you're not going to improve mail delivery with the  
first--use the second.



Merton Campbell Crockett
m.c.crockett at adelphia.net