macOS 26 breaks custom DNS settings including .internal
Summary
A bug report shows macOS 26.3.1 breaks the per-domain DNS resolver in /etc/resolver for private TLDs (like .internal). mDNSResponder intercepts queries for non-IANA TLDs and handles them via mDNS, effectively bypassing unicast DNS and disrupting local DNS workflows (dnsmasq, Docker, Kubernetes, Vagrant, VPN clients). The post outlines reproduction steps, impact on development environments, and a workaround using manual /etc/hosts entries.