1. See slides 33, 34, 35 from lecture 1.

2. Circuit-switched networks have resources pre-allocated, therefore they can
   provide service guarantees. They also provide lower end-to-end transmission
   delays for long, continuous messages. 

   Packet-swicthed networks allow for pipelining (overlap sending and receiving
   of packets on multiple links) and do not pre-allocate resources in advance.
   Therefore, they use more efficiently the capacity of the links.
   Additionally, they are fault-tolerant because they can use alternate
   routes when a path is broken.

3. See slides 40-44 from lecture 2.

4. Divide 11010111001000000 to 100011. The remainder is 0. So, no error is
   detected.

5. We need them for flow control and to recover from errors or lost packets.
   They are designed to use efficiently the link capacity. See slides 49-60
   from lecture 3.