සයිට්ස් බ්ලොක් කරන්නෙ කොහොම ද? පෝන් නෙමෙයි සාමාන්ය ඒවා... බුකිය කිරිය වගේ.
The easiest and stupidest way for an ISP to do it is by not resolving such sites eg: porn hub IP will be returned as 127.0.0.1.
The way to circumvent the above is to use another DNS server instead of ISP. Then you can just access those sites.
Now if the ISP is smart enough they will block any DNS traffic going out other than what goes to their servers
Some try using squid proxies. But when the site is SSL, you don't know what site they are accessing because the HTTP headers are all encrypted. So what they can do is figure out IPs of sites like pornhub and then block IP level access to them. That too is difficult because now sites don't just use single IPs they use shit like cdn which means they are really difficult to block.
But if you are a some company and want to control internet then you can use proxy solutions or even NGFWs since you have more control over your users.