Handling DNS for temporary address pools

Autonet uses temporary addresses for its dialin users. The good news is
that we're approaching 50,000 ports. The bad news is that this equates to
100,000 DNS database entries (forward and reverse). We're running BIND

Since the address <-> name mapping is deterministic (the address can be
derived from the name string, and the name string from the address) it
should be possible to hack BIND to recognise these addresses and respond.
Has anyone done anything like this?

For that matter, how do most people handle temporary address pools? Do
they even bother with DNSing them?

You've got to provide at least the reverse entries. Otherwise, many
websites will perform a lookup/timeout cycle that will delay the delivery
of pages several seconds (depending on the server). This will make your
users believe you have a "slow" connection, because they just see
their browser waiting.

Of course, you probably then want the forwards, because lots of sites
use paranoid wrappers to prevent DNS spoofing, and will deny you access.

Just my $0.02 worth. I plan to always DNS forward and reverse my ports.