> Problem is this:
> The last time my zone was transferred to my ISP, the INTERNAL names
> suddenly appeared on the internet! Of course this wrecked e-mail and
> other things as well, but how is this possible? How can the outside DNS
> provide the secondary with any information regarding the inside? BTW the
> inside network is not even accessible from the Internet (and thus the
> secondary DNS). Any ideas?
Make sure you run a (moderately) recent version of BIND, 4.9.3p1
Earlier versions may have some problems with cache poisoning even
in authoritative zones ...