Domain Name System resource records

Resource records are used to store data about domain names and IP addresses. You can use the Resource record lookup table to look into the resource records supported for the IBM® i operating system.

A DNS zone database is made up of a collection of resource records. Each resource record specifies information about a particular object. For example, address mapping (A) records map a host name to an IP address, and reverse-lookup pointer (PTR) records map an IP address to a host name. The server uses these records to answer queries for hosts in its zone. For more information, use the table to view DNS resource records.

Note: The entries in the resource record lookup table might be added or removed according to the change of the BIND document. Also, this is not a comprehensive list of all resource records listed in BIND.

Table 1. Resource record lookup table
Resource record	Abbreviation	Description
Address Mapping records	A	The A record specifies the IP address of this host. A records are used to resolve a query for the IP address of a specific domain name. This record type is defined in Request for Comments (RFC) 1035.
Andrew File System Database records	AFSDB	The AFSDB record specifies the AFS or DCE address of the object. AFSDB records are used like A records to map a domain name to its AFSDB address; or to map from the domain name of a cell to authenticated name servers for that cell. This record type is defined in RFC 1183.
Canonical Name records	CNAME	The CNAME record specifies the actual domain name of this object. When DNS queries an aliased name and finds a CNAME record pointing to the canonical name, it then queries that canonical domain name. This record type is defined in RFC 1035.
Host Information records	HINFO	The HINFO record specifies general information about a host. Standard CPU and operating system names are defined in the Assigned Numbers RFC 1700. However, use of the standard numbers is not required. This record type is defined in RFC 1035.
Integrated Services Digital Network records	ISDN	The ISDN record specifies the address of this object. This record maps a host name to the ISDN address. They are used only in ISDN networks. This record type is defined in RFC 1183.
IP Version 6 Address records	AAAA	The AAAA record specifies the 128-bit IPv6 address of a host. AAAA records, which are similar to A records, are used to resolve queries for the IPv6 address of a specific domain name. This record type is defined in RFC 1886.
Location records	LOC	The LOC record specifies the physical location of network components. These records can be used by applications to evaluate network efficiency or map the physical network. This record type is defined in RFC 1876.
Mail Exchanger records	MX	The MX records defines a mail exchanger host for mail sent to this domain. These records are used by Simple Mail Transfer Protocol (SMTP) to locate hosts that processes or forwards mail for this domain, along with preference values for each mail exchanger host. Each mail exchanger host must have a corresponding host address (A) records in a valid zone. This record type is defined in RFC 1035.
Mail Group records	MG	The MG records specifies the mail group domain name. This record type is defined in RFC 1035.
Mailbox records	MB	The MB records specifies the host domain name which contains the mailbox for this object. Mail sent to the domain is directed to the host specified in the MB record. This record type is defined in RFC 1035.
Mailbox Information records	MINFO	The MINFO records specifies the mailbox that should receive messages or errors for this object. The MINFO record is more commonly used for mailing lists than for a single mailbox. This record type is defined in RFC 1035.
Mailbox Rename records	MR	The MR records specifies a new domain name for a mailbox. Use the MR record as a forwarding entry for a user who has moved to a different mailbox. This record type is defined in RFC 1035.
Name Server records	NS	The NS record specifies an authoritative name server for this host. This record type is defined in RFC 1035.
Network Service Access Protocol records	NSAP	The NSAP record specifies the address of a NSAP resource. NSAP records are used to map domain names to NSAP addresses. This record type is defined in RFC 1706.
Public Key records	KEY	The KEY record specifies a public key that is associated with a DNS name. The key can be for a zone, a user, or a host. This record type is defined in RFC 2065.
Responsible Person records	RP	The RP record specifies the internet mail address and description of the person responsible for this zone or host. This record type is defined in RFC 1183.
Reverse-lookup Pointer records	PTR	The PTR record specifies the domain name of a host for which you want a PTR record defined. PTR records allow a host name lookup, given an IP address. This record type is defined in RFC 1035.
Route Through records	RT	The RT record specifies a host domain name that can act as a forwarder of IP packets for this host. This record type is defined in RFC 1183.
Services records	SRV	The SRV record specifies the hosts that support the defined services in the record. This record type is defined in RFC 2782.
Start of Authority records	SOA	The SOA record specifies that this server is authoritative for this zone. An authoritative server is the best source for data within a zone. The SOA record contains general information about the zone and reload rules for secondary servers. There can be only one SOA record per zone. This record type is defined in RFC 1035.
Text records	TXT	The TXT record specifies multiple strings of text, up to 255 characters long each, to be associated with a domain name. TXT records can be used along with responsible person (RP) records to provide information about who is responsible for a zone. This record type is defined in RFC 1035. TXT records are used by IBM i DHCP for dynamic updates. The DHCP server writes an associated TXT record for each PTR and an A record update that is done by the DHCP server. DHCP records have a prefix of AS400DHCP.
Well-Known Services records	WKS	The WKS record specifies the well-known services supported by the object. Most commonly, WKS records indicate whether tcp or udp or both protocols are supported for this address. This record type is defined in RFC 1035.
X.400 Address Mapping records	PX	The PX records is a pointer to X.400/RFC 822 mapping information. This record type is defined in RFC 1664.
X25 Address Mapping records	X25	The X25 record specifies the address of an X25 resource. This record maps a host name to the PSDN address. They are used only in X25 networks. This record type is defined in RFC 1183.