A DNS SOA (Start of Authority) record is a fundamental DNS (Domain Name System) record that provides essential information about a DNS zone. It signifies the start of authority for a particular zone and contains administrative details related to the management of the zone.

The SOA record is usually located at the beginning of a DNS zone file and includes the following information:

1. Primary Nameserver: The primary nameserver is the authoritative server that holds the master copy of the DNS zone. It is responsible for providing authoritative responses to DNS queries for the domain.
2. Email Address: The email address specified in the SOA record represents the responsible person or administrator for the DNS zone. This address is typically written in a specific format, such as “admin.example.com” (replace “example.com” with the actual domain).
3. Serial Number: The serial number is an incremental value that indicates the version or revision number of the DNS zone. It helps track changes made to the zone and is crucial for secondary nameservers to determine if the zone has been updated and needs synchronization.
4. Refresh Time: The refresh time defines how often secondary nameservers should check for updates to the zone. It indicates the interval (in seconds) at which secondary nameservers should query the primary nameserver for changes.
5. Retry Time: The retry time specifies the interval (in seconds) that secondary nameservers should wait before retrying a failed zone transfer or zone update request.
6. Expiration Time: The expiration time represents the maximum period (in seconds) during which secondary nameservers can continue to serve the zone without a successful refresh from the primary nameserver. After this time elapses, the zone is considered expired, and secondary nameservers should no longer serve it.
7. Minimum TTL (Time-to-Live): The minimum TTL determines the minimum duration (in seconds) that a DNS record should be cached by other DNS servers or clients. It sets a lower bound for the caching time, ensuring that changes to DNS records propagate within a reasonable time frame.

The SOA record is critical for the proper functioning of a DNS zone and helps ensure the integrity and synchronization of DNS data. It is automatically created and managed by the DNS server software. Changes to the SOA record typically require access to the DNS management interface provided by your domain registrar or DNS hosting provider.