SOA

SOA Record

Active

The SOA (Start of Authority) record is the first record in any DNS zone.

zone TTL IN SOA primary-ns admin-email serial refresh retry expire minimum

In one line

The SOA (Start of Authority) record is the first record in any DNS zone. It contains administrative information including the primary nameserver, responsible email address, and timing values that control zone transfers and negative caching (NXDOMAIN TTL).

Description

The SOA record marks the beginning of a DNS zone and contains essential administrative parameters. The serial number is incremented each time the zone changes, triggering secondary nameservers to update via zone transfers. The MINIMUM field defines the negative caching TTL – how long resolvers cache NXDOMAIN responses.

Examples

SOA record

shell

example.com.    86400    IN    SOA    ns1.example.com. admin.example.com. (
    2024011501  ; serial
    3600        ; refresh
    900         ; retry
    604800      ; expire
    300         ; minimum
)

Related Record Types

Specification

RFC 1035 – DNS SOA record specification →