A client with about 150 macOS called me. They needed to find a quick and effective way to flush DNS cache on macOS Terminal. After brewing a great cup of coffee from Guatelama I decided to take on this one.
I found a simple combination of commands using the macOS Terminal. Once you open your Terminal copy and paste the commands below and press enter:
sudo dscacheutil -flushcache;sudo killall -HUP mDNSResponder
You will not see a success confirmation message on the Terminal. After you run it try to ping or access the desired hostname.
You can even place this command on a bash script and deploy it to all your clients or ever for yourself (maybe create an alias in the Terminal).