DNS

Did you know - a domain name consists of a hostname, a domain name, and a top-level-domain (AKA TLD). For instance, in www.example.com, www is the hostname, example is the domain name, and com is the tld. www.example.com is known as the fully-qualified-domain-name (FQDN)

DNS Queries
Bind9 In 10 minutes
DNS zone file
PowerDNS - a DNS server designed to work with a database backend
Delegating sub-domains
djbdns