RFC compliance: MUST v SHOULD or MAY

[Nick Tait]

On 13/01/2025 12:44, Lee wrote:
> As long as I'm asking ignorant questions.. is there some reason why
> bind (at least as it came configured on my Debian machine) looks up
> .local names?
>
> I added this bit to named.conf to do what seemed reasonable.  But
> again - it seems reasonable _to me_ I dunno if anyone else agrees & it
> seems like either way is RFC compliant.
>
> zone            "local"       in { type master; notify no; file
> "/etc/bind/db.null"; };
>      #   https://tools.ietf.org/html/rfc6762
>      # This document specifies that the DNS top-level domain ".local." is a
>      # special domain with special semantics, namely that any fully
>      # qualified name ending in ".local." is link-local, and names within
>      # this domain are meaningful only on the link where they originate.
>      #
>      # Any DNS query for a name ending with ".local." MUST be sent to the
>      # mDNS IPv4 link-local multicast address 224.0.0.251 (or its IPv6
>      # equivalent FF02::FB).
>      #
>      # Implementers MAY choose to look up such names concurrently via other
>      # mechanisms (e.g., Unicast DNS) and coalesce the results in some
>      # fashion.
>      #
>      # "ping mypc.local." does a normal dns lookup followed by a
>      # link-local multicast name resolution to 224.0.0.252
>      # adding local to null.zone at least stops the normal dns lookup
>
>
> TIA,
> Lee

What is the problem you're trying to solve? E.g. If your goal is to have 
".local." domain names resolved using mDNS instead of DNS, then this is 
the wrong solution? You'd be better off starting with how name 
resolution is configured on the clients.

Nick.