### Quiz 1

• Each of the following 5 questions has a weight of 10, so your total score will fall into the [0-50] range.
• Be concise; if you have more than 15 lines in the answer, it is definitely too long. If you don't know the answer, don't leave me with some fluff to cover up the lack of knowledge; if you do, you have been warned: you are risking harsher marking.
• Write clearly. If I cannot decipher your scribbling, I will consider it non-existent.
• Sign each page of the submission with your name and student ID.

### GOOD LUCK!!!

1. Explain the difference between Frequency Division Multiplexing (FDM) and Time Division Multiplexing (TDM).

2. Define what a protocol is.

3. Describe the layered reference model of the Internet.

4. Design an application level protocol between two computers synchronizing their time. The final time should be the average of clock values taken from both computers. Make sure that only authorized computers participate in this exchange (i.e., the computers have to exchange a secret password).

5. Recall the car-caravan analogy from the lectures. Assume that a caravan of 10 cars travels on a freeway with a constant speed of 100 km/h. It is a toll road, so the caravan has to stop at tollbooths. It takes 12 seconds to process one car, but the whole caravan has to assemble at the booth before it can proceed ("store and forward"). Suppose that the caravan travels 200 km beginning in front of one tollbooth, passing through a second tollbooth and finishing just before a third tollbooth. What is the end-to-end delay?