How to troubleshoot DNS issues on macOS
Published: 28 January 2018
Filed Under: macOS
Below are a few methods and tools to help troubleshoot DNS on a Mac. This includes displaying the current DNS configuration, clearing your DNS cache, how to query a DNS server, and to even view the current DNS cache.
Display DNS configuration
To display your DNS configuration, run the following command from a terminal.
Clear DNS cache
Sometimes you need to clear you DNS cache. In order to do this, run the following commands from a terminal. Depending on your browser, you may need to also close your browser and clear it's own cache.
sudo killall -HUP mDNSResponder sudo dscacheutil -flushcache
Query DNS with nslookup
If you need to do simple lookups you can use nslookup to query a DNS server for a response.
# query default DNS server nslookup applesoap.com # query Google's Public DNS Server nslookup server 184.108.40.206 applesoap.com
Query DNS with dig
If you need a more advanced view or need to trace the steps of DNS query, the dig tool is very useful.
# query all results dig applesoap.com ANY # query A records dig applesoap.com A # query MX records dig applesoap.com MX # query NS records dig applesoap.com NS # query using a specific nameserver dig @ns-166.awsdns-20.com applesoap.com # trace the path taken of a query dig applesoap.com +trace
View DNS cache
Open Console, select your local machine, and search for mDNSResponder. Then open a terminal and type the command below. This will dump the current DNS cache into the console window.
sudo killall -INFO mDNSResponder