Addns.pl is a self-contained DynDNS update client for DynDNS.org (and possibly others). It supports a variety of IP detection methods including external webcheck/router pages. It also supports multiple configurations and hostnames, smart abuse prevention, and custom/static/dynamic DNS, and can run as a daemon, commandline options only, or with a configuration file.
Dents is a from-scratch implementation of the server side of the DNS protocol, sharing no code with any other project. Among its several features are compatibility with named, a modular driver system and an extensible control facility which allows the administrator to control the running server.
DNRD is a proxy DNS daemon. It supports several forward servers for redundancy and/or load-balancing. DNS queries for specific domains can be forwarded to a specific group of DNS servers (with redundancy and load balancing) for that domain. It is very useful in VPN and dialup environments but can also be used as a DNS cache or ad-blocker for networks and workstations.
Dnsmasq is a lightweight, easy to configure DNS forwarder and DHCP server. It is designed to provide DNS and (optionally) DHCP to a small network. It can serve the names of local machines which are not in the global DNS. The DHCP server integrates with the DNS server and allows machines with DHCP-allocated addresses to appear in the DNS with names configured either in each host or in a central configuration file. Dnsmasq supports static and dynamic DHCP leases and BOOTP/TFTP for network booting of diskless machines.