How to clear the DNS cache on a Qubes system?
Is restarting sys-net the right way to do this?
Any idea on this?
There are potentially several layers of caching involved (including outside of the Qubes system, if you’re using a router with a caching resolver like dnsmasq.
For the Qubes specific part, restarting the netvm and the appvm itself should take care of it. Whether you need to restart your router is for you to determine.
There is also in-application caching, as you may find in about:networking in firefox, and probably elsewhere in other browsers &c.