What is a resource record?

One unit of data in the domain name system. A resource record defines some attribute for a domain name such as an IP address, a string of text, or a mail route.
A resource record consists of five components:

1. fully qualified domain name.
2. TTL, time to live, in seconds.
3. Record class: Internet, Hesiod, or Chaos
4. record type: A,NS,MX, PTR, etc.
5. record data, depends on record type