We talked about DNS before and we talked about MX records and mail and DNS but now we’re going to talk about what else DNS can do.  Email uses the MX record type but there are a lot more record types for DNS out there than just mail.  In this post, we’re going to talk about one particular record, the SOA record.

Every domain has an SOA record, also known as a Start of Authority record.  Isn’t that a spiffy name?  Sounds like the delegation of authority in a business.  I shall start your authority here and here only!

I am your Start of Authority!

Every domain has a zone file that’s created by the administrator.  The top of that zone file has the SOA record and the rest of the zone file has all the records for the domain.

The SOA record that defines information about the domain itself.  It includes the name for the master name server, that’s the names server that is the be-all and end-all of information for the domain. Think of it as the server that is always going to have the real and true information of the domain.

It also includes an email address for the administrator.  This looks like a domain.  Like:  hostmaster.example.com.  That doesn’t look like an email address, where’s the @ sign?  Well, the first information before the dot is the email address, everything after it is the domain where the email is sent to.  That means that hostmaster.example.com is the email address hostmaster@example.com.

It also has a serial number for the domain.  Every time you make a change in the zone file, you change the serial number.  In the next post, we’ll talk about why the creators of DNS used this.