SOA Record

Start Of Authority records, or SOA records, are used by name servers to determine how a secondary name server will react. The parts of an SOA record include:

Name
This is the name that will represent the record. You will select this name when applying this record to a domain.

TTL
The number of seconds that this record will be cached in other servers.

Computer
The FQDN of the name server that was the original or primary source of data for this zone.

Email
A domain-name (FQDN) that specifies the mailbox of the person resonsible for this zone.

Starting Serial
The starting number that you want the serial number (the number version of your zone / domain). If you apply this SOA to a domain that is already created the serial number will just be incremented by one.

Refresh
The time interval (in seconds) before the zone should be refreshed.

Retry
The time interval (in seconds) before a failed refresh should be retried.

Expire
The time internal (in seconds) that specifies the upper limit on the time internal that can elapse before the zone is no longer authoritative. Basically when the name servers will expire if they are unable to refresh.

Negative Cache
The amount of time a record not found is cached.
Some older systems will treat the negative cache (how long a record not found answer is cached) as a minimum TTL for a record. For those older systems this is really not important since all records are required to have a TTL in the DNS Made Easy system. For the newer name servers that do treat this value correctly you should not set this value too high. Since a large value means that a record not found will be cached for that period of time.
If you know of a system that still treats this value as a minimum TTL you should do the Internet some good and tell the administrator to update their systems to at least year 2000 technology. Using software that is so old is generally not a good idea by any standard.