This topic explains how resource records are used by Domain Name System (DNS). Resource records are used to store data about domain names and IP addresses. This topic contains a searchable list of resource records supported for OS/400® V5R1.
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.
| 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 machine. 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 address of a host. AAAA records are used like A records to map a host name to its IP address. Use AAAA records to support IP version 6 addresses, which do not fit the standard A record format. 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. |
| 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 iSeries™ DHCP for dynamic updates. The DHCP server writes an associated TXT record for each PTR and A record update done by the DHCP server. DHCP records have a prefix of AS400 DHCP. |
| 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. |