a> I'd like to use AD integrated DDNS with
a> hidden masters for security and simplicity,
a> and then on the user enviroment to use the
a> standard secondaries, [...]
1. As I've said before, the concept of "hidden master" simply does not apply
to multi-master DNS database replication mechanisms such as Active Directory
integration. It embodies a notion of a single source of new database data
that simply does not exist.
2. Mixing and matching different DNS database replication mechanisms within a
single set of peer content DNS servers (as you are envisaging doing here by
mixing Active Directory integrated DNS database replication with "zone
transfer" DNS database replication) is something that one should not do unless
one is _very_ careful and knows _exactly_ what one is doing.
Both of these apply to _all_ DNS server softwares, not just to Microsoft's.
(BIND users coming to another DNS server software such as Microsoft's DNS
server often think that these facts are particular to that other server
software, because coming to that other software is the first place where they
encounter multiple DNS database replication mechanisms in common use. But in
fact it is the BIND world that is the odd one out with peculiar notions. In
the BIND world, there's really only one DNS database replication mechanism in
common use, "zone transfer", and the erroneous beliefs often propagate that
this is the _only_ DNS database replication mechanism and that what it does
with "masters", "slaves", and "SOA" resource records necessarily applies to
all DNS database replication mechanism. However, for most other DNS server
softwares, including Microsoft's, there are usually several DNS database
replication mechanisms, with "zone transfer" being the least functional and
most primitive of them, available and in common use, with different mastering
arrangements and with different usages for the fields in "SOA" resource
records.)