Say that we'll get super concrete this class.

Redo layering to make things clearer from last class.
1. Generality and layering: lots of confusion last class; explain again
2. Where layers are implemented: make this super concrete.

Talk about network performance
3. Network performance: throughput and latency.

Naming on the Internet
4. IP addresses (public vs. private), nats
5. Domain names and hierarcy in domain names and who allocates what.
6. DNS, hosts.txt, etc., dns caching

The sockets API and a real demo
7. UDP sockets
8. TCP sockets.
(Select is optional reading).