This is another CLI command, so get your terminal ready. This gives you a quickway to check the DNS settings on OSX. Now one way is to just cat /etc/resolv.conf , but what if you wanted to see what the system is actually using (not just what it was configured for). Well scutil comes to rescue and gives us an interface to the “dynamic store” data maintained by configd. Here is the command:
The output will list all four resolver your system is configured for. scutil is another one of those deep OSX commands, so I suggest you have a look at the manual for it (man scutil) or get on google and search for more details (Tech Zendo has a detailed article on how to perform actions during fast user switching, AFP548 also has a great article on how to setup NIC failover).