I am trying to block websites using:
1. DNS sinkhole - works, unless someone has website IP in cache (people from outside my network using Wifi - especially people with android devices doesn't clear their cache very long time)
2. layer 7 filtering - block video (but does not yt website), doesn't block youtube apps
3. tls host - block most of https websites (but not youtube)
4. block port 40, 443 tcp (for example) content: youtube -blocks acces to youtube website on mobile devices (only), doesnt block yt app.
5. blocking IP - works, but script has to be refreshed basically every one minute to work properly, it generates traffic and is invconvenient
I did tests on most popular webrowser - chrome and partially on firefox. As you see, any of mentioned methods isn't perfect. So tell me please, how are blocked webites in big companies&corporations (especially youtube) and countries like china ?