There are a couple easy possibilities depending on server config.
1. Not using SNI, and all https requests just respond with the same cert. (Example, go to https://209.216.230.207/ and you'll get a certificate error. Go to the cert details and you'll see the common name is news.ycombinator.com).
1. Not using SNI, and all https requests just respond with the same cert. (Example, go to https://209.216.230.207/ and you'll get a certificate error. Go to the cert details and you'll see the common name is news.ycombinator.com).
2. http upgrades to https with a redirect to the hostname, not IP address. (Example, go to http://209.216.230.207/ and you get a 301 redirect to https://news.ycombinator.com)