For a comprehensive look at Traffic Control, it is important to understand basic HTTP/1.1 protocol operations and how cache servers function.
For complete details on HTTP/1.1 see RFC 2616.
What follows is a sequence of events that take place when a client requests content from an HTTP/1.1-compliant server.
The client sends a request to the LDNS server to resolve the name
www.origin.comto an IP address, then sends an HTTP request to that IP.
A DNS response is accompanied by a TTL which indicates for how long a name resolution should be considered valid. While longer DNS TTLs of a day (86400 seconds) or more are quite common in other use cases, in CDN use-cases DNS TTLs are often below a minute.
GET /foo/bar/fun.html HTTP/1.1 Host: www.origin.com
The server at
www.origin.comlooks up the content of the path
/foo/bar/fun.htmland sends it in a response to the client.
HTTP/1.1 200 OK Content-Type: text/html; charset=UTF-8 Content-Length: 45 <!DOCTYPE html><html><body>This is a fun file</body></html>