RoundRobin question

[William Stacey]

Was wondering how round-robin is implemented at a high level.  Does each rr
in the zone have an integer value so that each time a rrset is returned for
say (www.mydomain.com A) each record will have some key that a sort is run
against that record set?  Then the record set is updated so the first rr
becomes the last on next sort?  Maybe the first rr get the count value of
the rrset so it is forced to the bottom and the rest get a sync starting at
1?  Just curious as was having talk on this with someone and am curious.
Cheers!

-- 
William Stacey