Resource records comprise the data within a DNS zone. There is no fixed limit to the number of resource records a zone can own. In general, there can be zero, one, or more resource records of a given type. However, there are constraints on the number of certain types of records a zone can have.
All resource records have these required entries:
Name —Name (host) that owns the record, such as example.com.
Class (not required for all formats) —DNS supports only the IN (Internet) class of record.
TTL (time to live)—Amount of time to store the record in cache, in seconds. If you do not include a TTL, Cisco Prime Network Registrar uses the zone default TTL, defined in the SOA resource record.
Type —Type of the record, such as A, NS, SOA, and MX. There are many types that various RFCs define, although ten or fewer are in common use.
Record data —Data types whose format and meaning varies with record type.
Table A-1 lists all the resource record types Cisco Prime Network Registrar supports. It provides the field syntax and the field descriptions, as well as how the fields are represented in the Cisco Prime Network Registrar GUI.