Midterm 1

Question 1

The OSI model consists of the following layers: Application, Presentation,
Session, Transport, Network, Data Link, and Physical. In your own words,
what does the Transport layer do? Explain your answer.

Answer 1

The transport layer of the OSI model handles the process to process channels

Question 2

The OSI model is sometimes called the 7 layer internet model. When
describing the layers of this model, the layers are sometimes referred to by
just their numbers. Which number is the Network layer?

Answer 2

Network would be the third layer.

Question 3

Explain the significance of the delay bandwidth product.

Answer 3

It’s the number of bits that can be in transit in a given instant and how many bits the sender must transmit before the first bit arrives at the receiver

Question 4

Give an example of an application which prefers to use UDP instead of TCP. Why does this application prefer to use UDP instead of TCP. Explain your answer.

Answer 4

Gaming would be where UDP would be more preferred compared to TCP. Gaming needs a fast connection, there is no delay from ACKs or retransmissions. Since UDP also runs the risk of packet loss, it’s acceptable for gaming. UDP has no congestion so UDP will send packets regardless of what happen.

Question 5

TCP is more complex that UDP. Identify 2 capabilities that TCP offers which UDP does not.

Answer 5

TCP is more reliable because it ensures that all packets are received correctly by using ACKs and retransmitting if packets are lost. UDP doesn’t guarantee delivery. TCP has congestion control to prevent packet loss and the overloading of data, UDP doesn’t have this and just sends the packets regardless.

Question 6

In TCP, how can a slow or overwhelmed receiver slow down or stop a fast sender?

Answer 6

TCP can stop a fast sender using the sliding window to manage how much data can be sent before needing an acknowledgement. Receiver advertises a window size. Sender adjusts transmission rate to not overwhelm the receiver. When the receiver sets the window size to 0, the sender stop until there’s more.

Question 7

Once a web server accepts a connection, what must it do to handle the web request while still being able to listen for additional connection requests?

Answer 7

Once a web server accepts a connection, to handle additional connection requests it must handle the request separately while continuing to listen for new connections using multithreading.