Infrastructure & ZoneRFC 1035

SOA Record — SOA Record (Start of Authority)

Specifies authoritative core parameters for the DNS zone including serial number, primary nameserver, and administrator email.

RECORD TYPE

SOA

STANDARD RFC

RFC 1035

DEFAULT TTL

86400 seconds (24 hours)

BIND Zone File Syntax Example

example.com.    86400    IN    SOA    ns1.cloudflare.com. dns.cloudflare.com. (
        2026090601 ; serial
        10000      ; refresh
        2400       ; retry
        604800     ; expire
        1800       ; minimum TTL
)

How to Query & Check SOA Records

Linux / Mac (dig)

dig +short SOA example.com

Windows / Generic (nslookup)

nslookup -type=SOA example.com

PowerShell (Resolve-DnsName)

Resolve-DnsName -Name example.com -Type SOA

Recommended Best Practices

Always follow the `YYYYMMDDNN` serial format (e.g. `2026090601`) so automated scripts and secondary nameservers can determine when zones have been modified.

Primary Use Cases:

•Controlling zone transfer replication timing between master and slave nameservers
•Setting negative caching TTL for non-existent domains (NXDOMAIN)

Common Configuration Mistake

Forgetting to increment the SOA serial number after making manual zone file changes, preventing secondary nameservers from updating.

Always verify records using authoritative queries (`dig @1.1.1.1 $SOA example.com`) to bypass local ISP caching when debugging propagation delays.

Frequently Asked Questions

DNS SOA Record Questions & Answers

Common questions regarding DNS propagation, TTL settings, and zone file syntax.

The SOA (Start of Authority) record marks the beginning of a DNS zone file. It contains the zone serial number (incremented on updates to trigger secondary nameserver replication), refresh, retry, expire, and minimum TTL intervals.

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