Lecture Topic: HTTP

# Conditional Get
## Last-Modified
You can check the Last-Modified header to only get contents if the contents are newer than the contents of the cache
## ETag
Use the hash of an object to check for modification to solve cache invalidation problem

## TCP and HTTP
HTTP runs on top of TCP
- Client initiates TCP request to server
- Server accepts TCP connection
- Clint confirms request
- Three way handshake

## Non-persistent HTTP
RTT = Round trip time
