djbdns is a collection of Domain Name System tools. It includes
several components:

- The dnscache program is a local DNS cache. It accepts recursive
  DNS queries from local clients such as web browsers. It collects
  responses from remote DNS servers.
- The tinydns program is a fast, UDP-only DNS server. It makes local
  DNS information available to the Internet.
- The pickdns program is a load-balancing DNS server. It points
  clients to a dynamic selection of IP addresses.
- The walldns program is a reverse DNS wall. It provides matching
  reverse and forward records while hiding local host information.
- The rbldns program is an IP-address-listing DNS server. It uses DNS
  to publish a list of IP addresses, such as RBL or DUL.
- The dns library handles outgoing and incoming DNS packets. It can
  be used by clients such as web browsers to look up host addresses,
  host names, MX records, etc. It supports asynchronous resolution.
- The dnsfilter program is a parallel IP-address-to-host-name converter.
- The dnsip, dnsipq, dnsname, dnstxt, and dnsmx programs are simple
  command-line interfaces to DNS. 
- The dnsquery and dnstrace programs are DNS debugging tools.
