Glossary
DNS root zone
The root zone is the top of the DNS: the list of every top-level domain and the name servers for each one. IANA maintains its contents, and it's served to the world by root servers under 13 names, a.root-servers.net through m.root-servers.net.
When a resolver looks up a name it doesn't know, it starts at the root, which points it to the right TLD's servers. Adding a TLD means adding it to the root zone — "delegation" — and removing one is "retirement".
The root zone has been DNSSEC-signed since July 2010, so resolvers can verify every TLD delegation cryptographically.
