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+## SSL / TLS Basics
+
+SSL refers to Secure Socket Layer and is a way to encrypt network traffic that is in flight.
+
+For AWS it refers to encrypting traffic between the client and the load balancer. Traffic between the load balancer and instances are handled over plain HTTP.
+
+The S in HTTPS refers to 'secure', which means the traffic is using SSL.    
+
+Nowadays, traffic is encrypted using TLS (Transport Layer Security), which is a newer version of SSL, but people still refer to it as SSL.
+
+SSl certs are issued by a Certificate Authority (CA) and have an expiration date. 
+
+![](assets/ssl.png)
+
+## Load Balancer and SSL
+
+- LB uses an X.509 Certificate
+- ACM (AWS Certificate Manager) manages certs
+- You must set a default SSL cert
+- Clients can use SNI (Server Name Indication) to specify the hostname they reach
+
+
+## Server Name Indication (SNI)
+
+- This helps manage multiple SSLs on one Server
+- Client must indicate server hostname to get the right SSL
+
+![](assets/sni.png)
+
+## Load Balancer Support
+
+- *CLB*: supports 1 SSL
+- *ALB*: supports multiple with SNI
+- *NLB*: support multiple with SNI