This is the eight installment In the of a ten-part series outlining the ten most common Domain Name System (DNS) Records.  In this article I will examine SOA Records, or Start of Authority Records.  Find links below to the previous articles:

• In the seventh article I examined PTR Records
• In the sixth article I examined SRV Records
• In the fifth article I examined TXT Records
• In the fourth article I examined MX Records
• In the third article I examined CNAME Records
• In the second article I discussed the AAAA Records
• In the first article I discussed the A Records

 

What is a soa Record?

The Start Of Authority Record contains administrative information about the DNS zone, typically regarding zone transfers.  A zone transfer is where one DNS server passes a copy of part of it’s database (which is called a “zone”) to another DNS server.  The SOA Record is governed by Request For Comments (RFC) 1035.

how are soa Records formatted

• NAME
  • Definition: The name of the zone
  • Recommended Setting for a stable zone:
• IN: This is the zone class, it’s normally IN for “internet”
• MNAME (Master Name):
  • Definition: Primary Master Name Server for the zone
  • Recommended Setting for a stable zone:
    • UPDATE requests should be forwarded toward the MNAME
    • NOTIFY requests propagate outward from the MNAME

• RNAME (Responsible Name):
  • Definition: the email address of the administrator responsible for this zone.
  • Recommended Setting for a stable zone: The format for email contact@jasonofflorida.com would be contact\.jasonofflorida.com since . are escaped with \
  • Parameters: 32 bit field

• SERIAL
  • Definition: The serial number for this zone. If a secondary name server slaved to this server observes an increase in this number, the slave will assume that the zone has been updated and initiate a zone transfer.
  • Recommended Setting for a stable zone:
  • Parameters: 32 bit field

• REFRESH
  • Definition: The time (in seconds) after which secondary name servers should query the master for the SOA record (to detect zone changes).
  • Recommended Setting for a stable zone: 86400 seconds, or 24 hours
  • Parameters: 32 bit field

• RETRY
  • Definition: The number of seconds after which secondary name servers should retry to request the serial number from the master, if the master did not initially respond.  It must be less than Refresh.
  • Recommended Setting for a stable zone: 7200 seconds, or 2 hours
  • Parameters: 32 bit field

• EXPIRE
  • Definition: The number of seconds after which secondary name servers should stop answering request for this zone, if the master did not respond.  This value must be bigger than the sum of Refresh and Retry.
  • Recommended Setting for a stable zone: 3600000 seconds, or 1000 hours
  • Parameters:
  • 32 bit field

• MINIMUM or Time To Live (TTL) 
  • Definition: I examined TTL extensively in the first article in this series discussing A Records.  T
  • Recommended Setting for a stable zone: 3600000 seconds, or 1000 hours
  • Parameters: 32 bit field

how do you set up soa RECORDs?

Some DNS providers have forms to add SOA Records, like you might any other DNS record. You can use the information above to populate the fields.  However, some providers, like GoDaddy do not offer configuration of the SOA Record:

 I see you’re using GoDaddy nameservers. We set up the SOA for all domains on these servers. You would not be able to edit the values of the SOA in this case. If you need something different, you might consider using a different DNS provider that offers this setting specifically.

If you received some added value from my post, please like and follow us on Facebook, Twitter, and LinkedIn, or subscribe to jasonofflorida.com.  Next in the DNS Records Series I will discuss the CAA Record, or Certification Authority Authorization.