DNS Delegation

DNS delegation is the mechanism by which authority over a child [[dns-zone|DNS zone]] is transferred from a parent zone to a separate set of [[nameserver|nameservers]], using [[ns-record|NS records]] in the parent zone that point to the child's authoritative servers. Delegation is the foundational principle behind the scalability of the [[dns|DNS]] hierarchy: [[iana|IANA]] delegates TLD zones to [[registry-operator|registry operators]], registries delegate second-level domains to [[registrar|registrars]], and domain owners can further sub-delegate subdomains. [[glue-record|Glue records]] (A records for the nameservers themselves) are added to the parent zone when a nameserver resides within the delegated zone to break circular lookup dependencies.