Check DNS SOA Records

An SOA record is a DNS record that defines the global parameters for a zone file (domain). Each zone file has exactly one SOA record.

SOA records are also called "Start of Authority records", and are defined in RFC 1035.

This page provides a brief overview of SOA records. A more detailed discussion is in our SOA Record Monitoring blog post.

DNS Check can monitor your SOA records, and notify you if they become unresolvable, or have any parameters change.

Fields

The SOA record is typically the most complex record in a zone file. Here are the fields that make up an SOA record:

Field Description Example
Name The fully qualified domain name (FQDN) of the zone file. dnscheck.co.
Type The DNS record type. Always set to SOA. SOA
Name Server An authoritative name server for the domain. Only one name server should be listed, even if the domain has multiple authoritative name servers. chan.ns.cloudflare.com.
Email The email address of the domain's administrator. The @ sign should be replaced with a dot (.). dns.cloudflare.com.
Serial Number This acts as the "version number" for the SOA record. It gets incremented each time the zone file that the SOA record is in gets updated. Valid values are 1 to 4,294,967,295. 2019756054
Refresh The time in seconds that a slave name server should wait before refreshing the zone file from the master. 10000
Retry The time in seconds that a slave name server should wait before retrying to establish a connection to the master following a communications error. 2400
Expire The time in seconds that may elapse before a zone file is no longer considered authoritative. 604800
Minimum The time in seconds to cache NXDOMAIN results in DNS. 3600

DNS Zone File Examples

Here's an example of how an SOA record which uses the example values from this page's Fields section looks in a DNS zone file:

; Name           Type  Name server              Email                Serial      Refresh  Retry  Expire  Minimum
dnscheck.co.     SOA   chan.ns.cloudflare.com.  dns.cloudflare.com.  2019756054  10000    2400   604800  3600

The Name, Name server and Email fields in the above example each end in a period, so they're using fully qualified domain names.

Alternatively, you can create an SOA record that's relative to the zone file's $ORIGIN. Here's an example of how to do this using the example values from this page's Fields section:

$ORIGIN dnscheck.co.
; Name           Type  Name server              Email                Serial      Refresh  Retry  Expire  Minimum
@                SOA   chan.ns.cloudflare.com.  dns                  2019756054  10000    2400   604800  3600

Additional Resources



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