SNI lets one IP host many TLS sites
Server Name Indication (SNI) sends the requested hostname in the TLS handshake, letting one IP address serve different certificates and sites. Without SNI, separate addresses were one solution, but a shared certificate covering several subject alternative names (SANs) or an appropriate wildcard could also serve multiple sites. The problem is ordering: in a full certificate-based HTTPS handshake without early data, certificate selection precedes the encrypted HTTP request that identifies the application. ...