How do hosting companies do realtime changes?

[Dan Vande More]

I've found myself in a situation where we'd like to offer the ability for
clients to update/add dns via a website.
I don't feel comfortable with a web server is running on my master server,
so that's not an option, so I was wondering how other people/companies do
it.
I've tested DLZ, but it seems far to slow for a web hosting provider(Or a
web hosting provider that prefers to be fast:)). I've also see that bind has
some built in APIs for databases, but it doesn't look like something that is
a 'professional' solution just yet.
I'm experimenting with perl scripts writing the confs and zone files, but
what is the best way to tell my master to regenerate the files, and reload
the zone from a remote machine?

And while perl is writing my named.conf or even a dns file, even if
everything is loaded into memory, will it affect the running named process?
(I.E. It takes a good 2 minutes to generate everything on a full rewrite.
Though if I did go this route, timestamps would affect which zone would be
regenerated.)

Sure there are tons of ways to do that, but which way to people feel most
comfortable with?

Is nsupdate an option?

How would I do reloads? When someone changes a record, or every 2-5 minutes,
etc.

I've formed several of my own conclusions, but I'm still in the alpha stage,
so any varying methods would be tremendously helpful.
I don't think a canned solution would help at this point, due to the
customizations I'd prefer, and from my searches of archives, most of the
linked ones will not work.

Thanks!

Dan Vande More