RFC1996 and IXFR dependency graph loops

[Ketil Froyn]

Hello.

Section 2.2 of RFC1996 states:

   2.2. The zone's servers must be organized into a dependency graph
   such that there is a primary master, and all other servers must use
   AXFR or IXFR either from the primary master or from some slave which
   is also a master.  No loops are permitted in the AXFR dependency
   graph.

I read this to mean that loops in IXFR dependency graphs are legal, but
loops in AXFR dependency graphs are not. Does anyone know the reason AXFR
loops are not allowed, and then the reason why IXFR loops are ok?

Thanks,
Ketil