How do Internet servers know I'm using a VPN?
I'm currently in my annual "Prairie Winter Avoidance Mode" in Saigon. I often use a VPN, mainly for secure banking transactions and occasionally to access web sites that are blocked here - the BBC for example.
I have frequently noticed that if I have my VPN activated, some websites cannot be accessed, until I turn off the VPN.
Is it just simply that the websites in question maintain a blacklist of IP addresses that are associated with VPN servers or is there something else going on?
PPRuNe's server definitely maintains a blacklist but at least the server tells me. None of the other sites do this - they just don't respond.