Types of DNS records
From XpertDNS
Important categories of data stored in the DNS include the following:
- An A record or address record maps a hostname to a 32-bit IPv4 address.
- An AAAA record or IPv6 address record maps a hostname to a 128-bit IPv6 address.
- A CNAME record or canonical name record makes one domain name an alias of another. The aliased domain gets all the subdomains and DNS records of the original.
- An MX record or mail exchange record maps a domain name to a list of mail exchange servers for that domain.
- A PTR Record or pointer record maps an IPv4 address to the canonical name for that host. Setting up a PTR record for a hostname in the in-addr.arpa domain that corresponds to an IP address implements reverse DNS lookup for that address. For example (at the time of writing), www.icann.net has the IP address 192.0.34.164, but a PTR record maps 164.34.0.192.in-addr.arpa to its canonical name, referrals.icann.org.
- An NS record or name server record maps a domain name to a list of DNS servers authoritative for that domain. Delegations depend on NS records.
- An SOA record or start of authority record specifies the DNS server providing authoritative information about an Internet domain, the email of the domain administrator, the domain serial number, and several timers relating to refreshing the zone.
- An SRV record is a generalized service location record.
- A TXT record allows an administrator to insert arbitrary text into a DNS record. For example, this record is used to implement the Sender Policy Framework specification.
- An NAPTR records (NAPTR stands for "Naming Authority Pointer") are a newer type of DNS record that support regular expression based rewriting.
Other types of records simply provide information (for example, a LOC record gives the physical location of a host), or experimental data (for example, a WKS record gives a list of servers offering some well known service such as HTTP or POP3 for a domain).
