[mavhc]

Except they appear to have done this in 2013, at least 13 years after people were using it for local internal dns

[eli]

Isn't that the point of reserving something like .internal? So that people don't "borrow" a TLD that could get assigned to something else later?

[mjevans]

.local wasn't a TLD and was too long to be likely to be assigned as a new country / .com like thing. It was in _wide_ use before mDNS and even vanity TLDs existed.

[throw0101d]

> It was in _wide_ use before mDNS and even vanity TLDs existed.

Yes, as noted in the RFC that reserved its use for mDNS:

    The special treatment of names ending in ".local." has been
    implemented in Macintosh computers since the days of Mac OS 9, and
    continues today in Mac OS X and iOS.  There are also implementations
    for Microsoft Windows [B4W], Linux, and other platforms.
    
    Some network operators setting up private internal networks
    ("intranets") have used unregistered top-level domains, and some may
    have used the ".local" top-level domain.  Using ".local" as a private
    top-level domain conflicts with Multicast DNS and may cause problems
    for users.  Clients can be configured to send both Multicast and
    Unicast DNS queries in parallel for these names, and this does allow
    names to be looked up both ways, but this results in additional
    network traffic and additional delays in name resolution, as well as
    potentially creating user confusion when it is not clear whether any
    given result was received via link-local multicast from a peer on the
    same link, or from the configured unicast name server.  Because of
    this, we recommend against using ".local" as a private Unicast DNS
    top-level domain.  We do not recommend use of unregistered top-level
    domains at all, but should network operators decide to do this, the
    following top-level domains have been used on private internal
    networks without the problems caused by trying to reuse ".local." for
    this purpose:

      .intranet.
      .internal.
      .private.
      .corp.
      .home.
      .lan.

* https://datatracker.ietf.org/doc/html/rfc6762#appendix-G

Key words: We do not recommend use of unregistered top-level domains at all….

The drafts for the RFC date back to 2001.

[Ferret7446]

If it wasn't a TLD, then it is invalid/undefined to attempt to use it as a TLD, so whether it works or not, or ceases to work in the future is fair game.

[throw0101d]

> Except they appear to have done this in 2013

The first mDNS draft came out in 2001. And as noted RFC 6762 § Appendix G, .local was used by Mac OS 9 for the same purpose as it it was for mDNS: link-local resolution.

[denkmoon]

So that this doesn't happen again is exactly why the defacto use of .lan should be codified in an RFC.

.local was never reserved for private use, and it got scooped up for mdns. .dev was never reserved for private use, it got gTLD'd and owned by Google who promptly put it on the HSTS preload list.

.internal is nice but it's not what people are already using.