Numbers on mx records

[base60]

Andy Pieters wrote:
> HI list
> Please forgive my ignorance but I used zoneedit to handle my dns (thanks to 
> this list) and now when I do a 
> 
> dig mx vlaamse-kern.com
> 
> it shows
> 
> 0 mail.vlaamse-kern.com
> 20 mta.pro.numericable.fr
> 
> Doing the same for other sites shows mx records starting with number 1
> 
> I know that these numbers determine the order, and that the higher the number 
> the lower the priority(?) but does 0 rather then 1 mean absolute priority?

A zero and a twenty means the same thing as a 10 and a 20: email goes to
the lower number, if possible.

The only thing that matters is the relative positions of the numbers.
The  absolute value is irrelevant.