skullgiver , 11 hours ago

It’s fine to use if you’re using it for Bonjour/mDNS (which is enabled by default on basically everything these days). If not, any computer in your network can take on a .local domain of their choosing and your computers will happily resolve it before hitting the DNS server, or you may end up in a race between normal DNS and mDNS. Or you can manually disable mDNS on every machine and hope nothing else causes conflicts, I guess.

If you need a TLD for fake internal domains, use .internal; that has recently been reserved for internal use and won’t end up in any standard protocols. There’s also a weaker blacklist list that’s part of the gTLD application process which includes .local, but that’s not necessarily set in stone.