The Roku media player has Google's free public DNS (18.104.22.168) hard-coded into it. This is great for DNS redundancy, but totally sucks if you use an unblock service to watch Netflix abroad (see this: How to Watch Netflix in Japan). From time to time my Roku would insist on using Google's DNS, so Netflix would no longer work properly. Boooo! There are 2 comparable ways to fix this:
Add a Null Route to Your Router
Most basic home routers allow you to add custom routes. Add a route to 22.214.171.124 that goes to the loopback address (127.0.0.1). Called a "null route," all traffic going to Google's DNS will simply be dropped. Problem solved.
Add a Rule to Your Firewall
If you have something more feature-rich than a basic home router, you can add a rule to your firewall that blocks access to 126.96.36.199. Be sure to include UDP as that's what DNS uses. The advantage of the rule approach is customizability. You can still allow other PCs on your network access to Google's DNS if desired.