Week 6: Muddiest points

The following queries may be beyond the scope of the class, but they are what confused me the most:

1. How does a switch function as a "multi-port bridge"?
2. How is backbone network different from a campus, or wide area network?
3. What are the technical and financial implications of adopting E2EE on a wider scale?
4. What constitutes the physical layer of a protocol stack?