Resource records are used to store domain information.DNS name servers contain resource records for those portions of the DNS namespace for which they are authoritative.
SOA (Start of Authority): Indicates that the server is the best authoritative source for data concerning the zone. Each zone must have an SOA record, and only one SOA record can be in a zone.
NS (Name Server): Identifies a DNS server functioning as an authority for the zone. Each DNS server in the zone (whether primary master or secondary) must be represented by an NS record.
A (Address): Provides a name-to-address mapping that supplies an IPv4 address for a specific DNS name. This record type performs the primary function of the DNS: converting names to addresses.
AAAA (Address): Provides a name-to-address mapping that supplies an IPv6 address for a specific DNS name. This record type performs the primary function of the DNS: converting names to addresses.
PTR (Pointer): Provides an address-to-name mapping that supplies a DNS name for a specific address in the in-addr.arpa domain. This is the functional opposite of an A record, used for reverse lookups only.
CNAME (Canonical Name): Creates an alias that points to the canonical name (real name) of a host identified by an A record.
MX (Mail Exchanger): Identifies a system that will direct email traffic sent to an address in the domain to the individual recipient, a mail gateway, or another mail server.
Srv (Service location): Makes it possible to find a server providing a specific service. Active Directory uses SRV records to locate domain controllers, global catalog servers, Lightweight Directory Access Protocol (LDAP) servers, and Kerberos servers. SRV records are created automatically.