macOS 26 breaks custom DNS settings including .internal
gist.github.com
March 19, 2026
5 min read
Summary
macOS 26.3.1 introduces a bug that breaks supplemental DNS resolution for custom TLDs in the /etc/resolver/ configuration. This issue is a regression from the previous version, macOS 25.x 26.3.0, which functioned correctly.
Key Takeaways
- macOS 26.3.1 has a regression that breaks the /etc/resolver/ mechanism for custom TLDs, which worked correctly in macOS 25.x.
- The mDNSResponder in macOS 26 intercepts queries for custom/private TLDs and does not consult the specified unicast nameserver, leading to failures in local development and private network DNS workflows.
- Tested TLDs that are affected include .internal, .test, and .home.arpa, all of which fail to resolve correctly in macOS 26.
- The issue results in applications using getaddrinfo() failing to resolve custom domains, returning "Unknown host" errors instead.
Community Sentiment
NegativePositives
- Using *.localhost for local web development simplifies DNS management, allowing for easier access to local resources without additional configuration, which can enhance developer productivity.
Concerns
- macOS 26 introduces significant breaking changes that complicate app development, such as restrictions on brightness settings for displays, which directly impacts user experience and functionality.
- The reliance on LLMs for bug reports raises concerns about accuracy and validation, potentially leading to mistrust in the reporting process and delaying necessary fixes.
Source
gist.github.com
Published
March 19, 2026
Reading Time
5 minutes
Relevance Score
65/100
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