SNI

Problem

One server IP hosts: shop.com news.com bank.com TLS needs to choose the correct certificate very early in connection establishment. Which hostname is the client trying to reach?

Solution — Server Name Indication

The client includes the intended server name during the TLS handshake.

Client:
"I want shop.com"
      ↓
Server chooses shop.com certificate

Core idea: SNI lets multiple TLS hostnames share the same server/IP infrastructure.