captivednsd, the Captive Domain Name Server, returns same authorative response to every query. The reponse to 'A' queries and 'PTR' records are passed as a parameter on the command line. The code is covered by the GNU General Public License.
I wrote the daemon to direct people to a captive web portal, on a system that was not connected to the Internet. This meant that it was not possible to resolve the correct IP address for a host and then redirect the query using a firewall.
captivednsd is based on the source code of scdns and Busybox's dnsd:
captivednsd [options] <ip> <host> -t <ttl> Set the TTL for DNS responses (default 30). -p <port> Port number to listen on (default 53). -b <addr> Bind to an IP address (default 0.0.0.0).
$ captivednsd 10.0.0.1 portal.local.
All A requests will return IP address 10.0.0.1.
All PTR requests will return portal.local.