sheerdns is a master DNS server whose zone records are stored on a
one-record-per-file bases. Because of this, sheerdns is likely the
simplest DNS to configure, use, update, and operate. It's especially
efficient for networks with frequent updates -- serving DHCP, for example.
Updates to the zones are immediate, and do not require restarting sheerdns.

SheerDNS is a good candidate for creating and RBL for mail, or web sites,
as well as for providing DNS on embedded systems. Or anything else that
requires a fast DNS, with very low overhead.

WWW: https://BSDforge.com/projects/dns/sheerdns/