I'm learning about encryption and SSL certificates and I'm wondering: If an encrypted connection is used when connecting to a website using a SSL certificate, how can ISP/company manager/government (whoever controls the network traffic) block some specific content of that website?.
I know from this question that an entire website/domain(IP address) can be blocked since the server IP is not encrypted at the TCP layer, otherwise no way to make a connection!. But since an encrypted connection is established, all data traffic is encrypted - including the request headers (like URL header) -, So ISP's don't know if the request is for
because the entire URL is encrypted along with the entire request to the receptionist.
My problem now is, how could some ISP's block some videos on YouTube about 4 years ago?.
I wasn't aware of something called encryption 4 years ago to think about it, but now I'm trying to understand what was going on that time.
The only Explanation I could come up with Is that YouTube was allowing
http requests at that time . So an
http request to
can be blocked , but a an
https request to the same URL can not be blocked because the ISP doesn't know what is being watch!. I don't know if my explanation is right or wrong, but I hope I can understand.