SOA

SOA (Start of Authority) is a DNS record that contains essential information about a DNS zone, including the primary nameserver, administrator email, and timing parameters for zone transfers and caching.

The SOA record is a mandatory DNS resource record that defines the authoritative nameserver for a domain and contains metadata about the DNS zone. Every domain must have at least one SOA record to function properly on the DNS.

The SOA record includes several critical fields: the primary nameserver (MNAME), responsible administrator email (RNAME), serial number (for tracking zone changes), and timing values like refresh interval, retry interval, expire time, and minimum TTL. These timing values control how often secondary nameservers update their copies and how long DNS resolvers cache the record.

Example SOA record for example.com:

example.com. 3600 IN SOA ns1.example.com. admin.example.com. 2024010101 3600 1800 604800 86400

This indicates ns1.example.com is authoritative, [email protected] is responsible, secondary servers check for updates every 3600 seconds, and the record expires after 604800 seconds if unreachable.

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