off-site slave servers? advice?

Dear bind-users,

Right now, my domain has 5 on-site nameservers (1 master, 4 slaves)
and 1 off-site slave on a different campus. There has been talk of
adding yet another off-site slave in a different location, which
brings up this topic.

We run bind 9.2.1, and we've noticed (since upgrading from bind 8)
that many domains that used to resolve now do not resolve. When
looking for the reason why, it always turns out that one of the
non-resolving domains has a nameserver that isn't responding or
that responds incorrectly. It seems that bind 8 was much more lenient
in this regard, is that true?

So, here's the reason for my worry:
We want another off-site nameserver because we want people to be
able to reach our main website (which will be mirrored elsewhere)
if we're down for an extended period of time. However, since bind 9
doesn't seem to want to resolve domains where one of the nameservers
doesn't respond, will having one off-site nameserver that is responding
even help us if the other 5 are down?

Can anybody explain in detail how this is supposed to work, and give
their opinion about whether or not we should be looking into this?

Thanks.
Loren

--
loren jan wilson, CCNA
network engineering, uchicago.edu