Documentation

For OPT records (EDNS0), this defines the maximum message size instead.

see Message::CLASS_IN constant (UINT16)

The payload data format depends on the record type. As a rule of thumb, this library will try to express this in a way that can be consumed easily without having to worry about DNS internals and its binary transport:

• A: IPv4 address string, for example "192.168.1.1".

• AAAA: IPv6 address string, for example "::1".

• CNAME / PTR / NS: The hostname without trailing dot, for example "reactphp.org".

• TXT: List of string values, for example ["v=spf1 include:example.com"]. This is commonly a list with only a single string value, but this technically allows multiple strings (0-255 bytes each) in a single record. This is rarely used and depending on application you may want to join these together or handle them separately. Each string can transport any binary data, its character encoding is not defined (often ASCII/UTF-8 in practice). RFC 1464 suggests using key-value pairs such as ["name=test","version=1"], but interpretation of this is not enforced and left up to consumers of this library (used for DNS-SD/Zeroconf and others).

• MX: Mail server priority (UINT16) and target hostname without trailing dot, for example {"priority":10,"target":"mx.example.com"}. The payload data uses an associative array with fixed keys "priority" (also commonly referred to as weight or preference) and "target" (also referred to as exchange). If a response message contains multiple records of this type, targets should be sorted by priority (lowest first) - this is left up to consumers of this library (used for SMTP).

• SRV: Service priority (UINT16), service weight (UINT16), service port (UINT16) and target hostname without trailing dot, for example {"priority":10,"weight":50,"port":8080,"target":"example.com"}. The payload data uses an associative array with fixed keys "priority", "weight", "port" and "target" (also referred to as name). The target may be an empty host name string if the service is decidedly not available. If a response message contains multiple records of this type, targets should be sorted by priority (lowest first) and selected randomly according to their weight - this is left up to consumers of this library, see also RFC 2782 for more details.

• SSHFP: Includes algorithm (UNIT8), fingerprint type (UNIT8) and fingerprint value as lower case hex string, for example: {"algorithm":1,"type":1,"fingerprint":"0123456789abcdef..."} See also https://www.iana.org/assignments/dns-sshfp-rr-parameters/dns-sshfp-rr-parameters.xhtml for algorithm and fingerprint type assignments.

• SOA: Includes master hostname without trailing dot, responsible person email as hostname without trailing dot and serial, refresh, retry, expire and minimum times in seconds (UINT32 each), for example: {"mname":"ns.example.com","rname":"hostmaster.example.com","serial": 2018082601,"refresh":3600,"retry":1800,"expire":60000,"minimum":3600}.

• CAA: Includes flag (UNIT8), tag string and value string, for example: {"flag":128,"tag":"issue","value":"letsencrypt.org"}

• OPT: Special pseudo-type for EDNS0. Includes an array of additional opt codes with a value according to the respective OPT code. See Message::OPT_* for list of supported OPT codes. Any other OPT code not currently supported will be an opaque binary string containing the raw data as transported in the DNS record. For forwards compatibility, you should not rely on this format for unknown types. Future versions may add support for new types and this may then parse the payload data appropriately - this will not be considered a BC break. See also RFC 6891 for more details.

• Any other unknown type: An opaque binary string containing the RDATA as transported in the DNS record. For forwards compatibility, you should not rely on this format for unknown types. Future versions may add support for new types and this may then parse the payload data appropriately - this will not be considered a BC break. See the format definition of known types above for more details.

hostname without trailing dot, for example "reactphp.org"

For OPT records (EDNS0), this defines additional flags instead.

maximum TTL in seconds (UINT32, most significant bit always unset)

see Message::TYPE_* constants (UINT16)