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Mac OS X: finding the DNS servers available

Posted by jpluimers on 2016/07/01

DNS and Mac OS X are a bit of a tricky situation as OS X can use more than the default DNS servers: its resolve can do a multi-client DNS search.

The default DNS servers can be listed like this:

scutil --dns | grep 'nameserver\[[0-9]*\]' | sort | uniq

The effective DNS server like this:

dig whoami.akamai.net | grep "^;; SERVER" | cut -c 12-

Sometimes you want to know if you have manually configured DNS servers, or only DHCP assigned ones. This statement shows that for my Wi-Fi network-service:

networksetup -getdnsservers Wi-Fi

Because of the multi-client setup, you need to run this for all network-services configured on your OS X installation. You can get the list like this:

networksetup -listallnetworkservices

I’ve not yet found a way to list only active services, as the networksetup documentation indicates the -listnetworkserviceorder option will mark inactive ones with (*), but it reality does so only for disabled ones. So this does not work:

networksetup -listnetworkserviceorder

I might one day dig into combining the output of ifconfig with networksetup to figure out a shell based solution to this question.

–jeroen

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