DNS database is a collection of resource records and each records point to a particular object.
These are the resource records:
1. Address Mapping (A) Record :
This record maps the host name to the IP address. RFC-1035
2. Pointer(PTR)Record :
This record maps the IP address to the hostname.RFC-1035
3. Canonical(CNAME)Record :
Also called Alias name. This is an alias name for a host. RFC-1035
4. AAAA Record :
It resolves host name to IPv6 . RFC-3596
5. Mail Exchange (MX) Record :
These records are used for locating SMTP host responsible for delivering emails. RFC-1035
6. Start of Authority (SOA) Record :
It specifies the server authoritative for the zone. It defines the zone name, an e-mail contact and other time and refresh values. RFC-1035
7. Service (SRV) Record :
It defines services available in the zone like, finger, ldap, time and so on. RFC-2872