Each domain name has one or more resource records
associated with it. Resource records are 5-tuples:
Domain_name TTL Type Class Value
Domain_name
the name of the domain to which this RR applies.
TTL
the Time To Live of this RR. When this RR is
returned as a result of a DNS lookup, the remote host normally
caches the information for efficiency. The TTL is the time, in
seconds, after which the cached information should be regarded as
potentially out of date.
Type
there are several types of RR, including:
SOA
Start Of Authority.
A
IP address of a host.
NS
Name Server, etc
Class
Always set to "IN", for Internet
Value
The actual value of this particular RR. Can be, for example, an
IP address, a number, some ASCII text or a combination.