The GPO wants this for the protogeni racks. We now build reverse
map files for the 172.16 subnet, although we do it on a /16 boundry
to avoid a zillion zone files.

I am not planning to write an update script for this, since it would
require scripting changes to named.conf, which I am loath to do. So I
will do it by hand in Utah, and new sites (racks) will get it. If a
site wants it:

	boss> cd obj/named

Copy all of the 172 files to /etc/named/reverse
Copy all of the 172 zone entries from named.conf to /etc/named/named.conf

	boss> named_setup