The SOA (start of authority) resource record. The SOA indicate that this name server is the authorotative source of information for this domain. There can be only one SOA for a domain.
- Primary - what is the primary Start Of Authority for this domain
- rootmail - who is to get mail for the domain master
- Expire - seconds for secondary DNS server to expire it's data after failing to reach master
- Retry - how often the secondary DNS server should try to connect after a refresh connect failure
- Refresh - how often the secondary should check to insure it's data is current
- Minimum - the time a RR can be cached before it should be discarded
