beware is a small DNS server that can have nameserver responsibility delegated to it and that can return a set of authoritative "IN A" records to a client. Given a list of hosts for a certain domain name, it also tests for services specified and will only return IP addresses for currently reachable services.
Unnamed un-names unwanted DNS entries. It was written to solve the problem of upstream DNS servers inserting bogus records for NXDOMAINs. It can be used to filter unwanted domain names like ads, porn, time wasters, etc. It is modular, so extensions are easy. Extensions can be written in Lua or compiled as shared objects.
Bind DLZ on Rails is a Web-based user interface for managing BIND with the bind-dlz extensions on a MySQL 5.0 backend. BIND is a DNS server, and the bind-dlz extensions enhance BIND with support for database backeneds. This simplifies the management of thousands of zones and provides added redundancy (by way of database replication).
pymds is a simple, authoritative-only DNS server that has a simple module system for customizing how name resolution happens. The main motivation for starting this project was to create a simple system for building smarter DNS servers, capable of geography awareness, geographic load balancing, application aware load balancing, etc. Current modules implement standard behavior of using a file based DB to answer queries and to provide simple round-robin load-balancing across several servers by altering the order that IP addresses are returned.