When sending data over HTTPS, I know the content is encrypted, however I hear mixed answers about whether the headers are encrypted, or how much of the header is encrypted.

How much of HTTPS headers are encrypted?

Including GET/POST request URLs, Cookies, etc.

Solution 1:

The whole lot is encrypted^† – all the headers. That’s why SSL on vhosts doesn’t work too well – you need a dedicated IP address because the Host header is encrypted.

^†The Server Name Identification (SNI) standard means that the hostname may not be encrypted if you’re using TLS. Also, whether you’re using SNI or not, the TCP and IP headers are never encrypted. (If they were, your packets would not be routable.)