slapi-dnsnotify is a plugin for OpenLDAP or other LDAP servers. It watches for changes in the serial number of a DNS zone stored in the LDAP server, and notifies DNS slave servers to refresh their copy of the zone. It can also increment the serial number of a zone whenever changes in that zone are made.
dnscacheaudit is a simple Perl utility to audit entries in the BIND cache. At the end of each run, it creates a PDF report showing the number of domains in the BIND cache that have a different IP address in the cache than the reference servers. This utility is inspired by the CacheAudit utility by Jose Avila.
nspamper is an event driven client to update dynamic DNS entries via Nsupdates. It robustly copes with network problems by retrying until DNS returns the the new IP address. It also correctly handles the case where the link dropped and re-established before the last attempt succeeded by using the latest IP address. Only a minimum of configuration options are required.
dns.c is a recursive, re-entrant, non-blocking DNS resolver in a single .c file. It features a record-agnostic API, restartable record iterators, and smart queries which recursively follow out-of-bailiwick NS, MX, and SRV host references. It works just as well as a stub resolver, too. It also includes spf.c, a non-blocking SPF resolver with no threading, no forking, and no run-time dependencies.
adsuck is a small DNS server that spoofs blacklisted addresses and forwards all other queries. The idea is to be able to prevent connections to undesirable sites such as ad servers, crawlers, etc. It can be used locally, for the road warrior, or on the network perimeter in order to protect local machines from malicious sites.