Test your DNS server using Network Utility on Mac
Use Network Utility to view information provided by your Domain Name System (DNS) server.
Your DNS server converts internet names to IP addresses. If you get a message such as “server not found” from your web browser when you try to visit a website, your computer may be unable to contact a DNS server. You may have entered the wrong DNS server address in your Network preferences or your DNS server may be having problems. To test, try converting a name to an address using Network Utility.
On your Mac, open the Network Utility app , located in the /System/Library/CoreServices/Applications folder.
Click Lookup, then enter an internet address to look up.
Type a domain name address (for example, www.apple.com) or a numerical IP address, then click the Lookup button.
To find out which DNS server you should be using, check with your ISP or network administrator.
For help interpreting the results or to see how you can use the underlying nslookup or dig command to see more DNS information, open Terminal (in Applications > Utilities), then type man dig at the command line.