http://bind-dlz.sourceforge.net/
BIND DLZ is a patch for BIND 9 that enables DLZ (Dynamically-Loaded Zones). This project was an effort to make it easier to manage large-scale DNS environments with respect to adding new zones on the fly and maintaining existing ones.
Until BIND 9 added dynamic zone additions and deletions (version 9.7.2), this could become a problem when operating at scale. See the Adding new zones to busy BIND servers below.
BIND-DLZ remained relevant after the advent of BIND 9's dynamic adds and deletions because it made it possible to run a BIND 9 nameserver using alternative backend data stores for the zone data, such as MySQL, PostgreSQL, and LDAP. However, BIND has also since added its own DLZ drivers, accomplishing much of the same functionality.
Those considering a method to enable database storage for DNS zonedata may be better off looking...