DNS Attrleaf Changes: Fixing Specifications That Use Underscored Node Names
Using an underscore for a prefix creates a space for constrained interoperation of resource records. Original uses of an underscore character as a domain node name prefix were specified without the benefit of an IANA registry. This produced an entirely uncoordinated set of name-creation activities, all drawing from the same namespace. A registry for these names has now been defined by RFC 8552. However, the existing specifications that use underscored naming need to be modified in order to be in line with the new r
What it is
Cleans up the convention of putting underscores in DNS names, such as _dmarc and _domainkey, and registers them properly.
What it solves
Underscore-prefixed names grew ad hoc across many specifications with no registry, so collisions were possible.
What it means to operate
Mostly housekeeping. It matters if you run DNS tooling that validates hostnames, because underscore labels are legal here and some validators reject them.
Domain check resolves the underscored names email actually uses, so a missing one shows up as missing. Open domain check
Normative requirements
Every sentence in this RFC carrying an RFC 2119 keyword, with the section it came from.
3.1 SRV Specification Changes
- SHOULDThe SRV RRset 'protocol' (global) underscored node name SHOULD be registered in the IANA "Underscored and Globally Scoped DNS Node Names" registry [RFC8552].
3.2 URI Specification Changes
- SHOULDAs for the SRV RRset [RFC2782], the URI RRset global (highest- level) underscored node name SHOULD be registered in the IANA "Underscored and Globally Scoped DNS Node Names" registry [RFC8552].