| /AliasMode /Client |
Contents
The SVCB RR has two modes:
1) AliasMode (Section 2.4.2), which aliases a name to another name and 2) ServiceMode (Section 2.4.3), which provides connection information bound to a service endpoint domain.
Placing both forms in a single RR type allows clients to fetch the relevant information with a single query (Section 2.3).
1. history
The SVCB RR has two required fields and one optional field. The fields are:
SvcPriority (Section 2.4.1): The priority of this record (relative
to others, with lower values preferred). A value of 0 indicates
AliasMode.
TargetName: The domain name of either the alias target (for
AliasMode) or the alternative endpoint (for ServiceMode).
SvcParams (optional): A list of key=value pairs describing the
alternative endpoint at TargetName (only used in ServiceMode and
otherwise ignored). SvcParams are described in Section 2.1.2.1. Zone-File Presentation Format
The presentation format <RDATA> of the record ([RFC1035], Section 5.1) has the form:
SvcPriority TargetName SvcParams The SVCB record is defined specifically within the Internet ("IN") Class ([RFC1035], Section 3.2.4).
2.2. RDATA Wire Format
The RDATA for the SVCB RR consists of:
a 2-octet field for SvcPriority as an integer in network byte order.
the uncompressed, fully qualified TargetName, represented as a
- sequence of length-prefixed labels per Section 3.1 of [RFC1035].
the SvcParams, consuming the remainder of the record (so smaller
- than 65535 octets and constrained by the RDATA and DNS message sizes).