"You can install your own wifi router behind the cable modem. At that point you could change the settings that the router hands out for DNS.
"The pi-hole project shows how to change the settings where they point to your local pi-hole server and it forwards anything unknown to a location of your choice." Another similar option that is both very secure and good performing is to use a dns-caching server on the Linux pc. Your PC only makes 1 query to a public DNS and then stores the ip address locally that is used for all subsequent queries to for that domain name. It has been many years since I've done this and I think I used DjbDNS or TinyDNS on my Debian system. I suspect if you search your package manager app for "dns cache", you'll find a DNS caching server app that you can install and then Google search for configuration instructions. s
