macOS 26 breaks custom DNS settings including .internal

6 hours ago

macOS 26.3.1 breaks `/etc/resolver/` DNS configuration for custom TLDs.
The issue affects TLDs not in the IANA root zone, including `.internal`, `.test`, `.home.arpa`, and `.lan`.
`mDNSResponder` intercepts queries for custom TLDs, treating them as mDNS, bypassing specified unicast nameservers.
This regression from macOS 25.x silently fails, with no DNS traffic reaching configured local DNS servers like dnsmasq.
Workarounds include manually adding entries to `/etc/hosts`, but this is impractical for dynamic environments.
The bug impacts local development setups, Docker, Kubernetes tools, and VPN clients relying on custom TLDs.
Documentation and diagnostics (`scutil --dns`) misleadingly show correct configuration, masking the underlying issue.

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