How to detect if DDNS is supported?

[Dan Nicolae]

Does anyone know or can suggest a method of auto-detecting from the client
side if Dynamic DNS is supported and/or enabled at the Primary?

I've been witnessing the slow introduction of Windows 2000 computers in a
network with DNS based on BIND servers. Because DDNS is enabled by default
on W2K the Windows machines keep sending UPDATE packets every 30 seconds or
so to the BIND primaries where DDNS is either not supported or disabled.
This fills up the log files and makes DNS admins go nuts and instruct
everyone how to disable the evil DDNS.

I was thinking of a way to detect if DDNS is supported and enabled at the
Master. If it turns out negative the DDNS clients would disable themselves
and stop sending the unwanted UPDATE packets. First it came to my mind that
it would be enough to stop sending UPDATEs if we get back a NOTIMP. But it
turns out that we can also get a REFUSED if updates are supported but not
enabled. This makes things even worse because the clients would interpret
that as a lack of credentials and would keep hitting the master with signed
UPDATE packets this time.

Anyone has any idea about how to implement this auto-detection on the client
side?

If not, could BIND be modified so that only returns REFUSED when the client
does not have sufficient rights to perform the UPDATE and to return NOTIMP
if the server either does not support DDNS (I believe this is in already) or
the zone does not allow dynamic updates?

Thanks for any input,
Dan