This question already has an answer here: How is DNS lookup configured for OSX Mountain Lion? 2 answers In resolver manual, it said: The address may optionally have a trailing dot followed by a port number. For example, 10.0.0.17.55 specifies that the nameserver at 10.0.0.17 uses port 55. But it doesn't work, in /etc/resolv.conf or files under /etc/resolver/. 208.67.222.222.5353 Can I specify non-default port number for nameserver in osx? Update: osx don't use /etc/resolve.conf, but use files under /etc/resolver/. I have wrote a file dev with content '127.0.0.1' to route all dns queries for *.dev domains to a local dns server (127.0.0.). But I cannot specify dns server's port here. (It uses 53 anyway) Maybe there is no way to specify port number under osx?