DNSzone

A DNSzone, often written as DNS zone or DNSzone, is a portion of the Domain Name System namespace that is administered as a single unit. It is delegated to one or more authoritative name servers and contains the resource records that define the domain names within its authority. A zone boundary is established by DNS delegations and often corresponds to a domain name (the zone apex).

Zones are implemented as zone files on primary servers, though secondary servers can hold copies via zone transfers. The zone file includes an SOA (start of authority) record, NS records for the zone's authoritative servers, and other resource records such as A, AAAA, MX, CNAME, TXT, and PTR. The SOA includes the zone serial number, refresh and retry intervals, and expiry and minimum TTL, which control data consistency.

Delegation and transfers: A zone can have subzones delegated to other zones by NS records and separate zone files. Primary (master) and secondary (slave) configurations support redundancy. Zone transfers (AXFR for full or IXFR for incremental) replicate data to secondaries.

Security and updates: DNSSEC signs zones to provide data integrity and authenticity; parent zones hold DS records linking to the child zone's DNSKEY. Zones can be updated dynamically (RFC 2136) or by updating the zone file and reloading the zone. TTL values influence caching and update behavior.

Purpose and scope: Zones enable scalable, delegated administration of names within the DNS, aligning technical boundaries with organizational or geographic structures.