I've added an example external DLZ driver with update support here: http://git.samba.org/?p=tridge/bind9.git;a=blob;f=contrib/dlz/example/dlz_example.c;;hb=master This should provide a reasonable example for anyone who might want to extend an existing DLZ driver to add update support, or build it outside the bind9 tree. Cheers, Tridge