This error happen when try running google SpeedTest.
some of the solution to try:
This is from/source: https://www.bleepingcomputer.com/forums/t/529115/dns-lookup-failed-i-hav...
Click windows button --- type cmd --- on the shortcut, right click and Run as Admin -- type ipconfig /flushdns press enter
click windows button --- Control panel --- under Network and Internet click View network status and tasks -- upper left click change adapter settings -- right click on your connection, Local area connection is if you're wired, Wireless Network Connection if wireless --- click Properties -- click to highlight Internet Protocol Version 4 --- click Properties button -- click Use the following DNS server addresses and in the boxes type 126.96.36.199 as Preferred and 188.8.131.52 as Alternate -- click OK, Close and close network connections -- reboot your computer and try it.
Those 2 things flushed all DNS entries in your DNS cache and then we changed the default DNS servers to OpenDNS servers, some of the best out there. Report back what happens for you.