Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

Q1.1 Name two layer-4 protocols, explain what they do, and describe their differ

ID: 666870 • Letter: Q

Question

Q1.1 Name two layer-4 protocols, explain what they do, and describe their differences. What is a packet switch? What is a circuit switch? What is a message switch? Give two examples of packet-switched networks and explain how they work. Q1.2 Q1.3 What is processing delay? What is queuing delay? What is transmission delay? What is propagation delay? Explain why a network system should be designed to have a traffic intensity of no greater than Computer Science 347: Computer Networks Page 1 of 3 List at least three different ways a home computer may be connected to the Internet, and use a table to summarize their features, advantages, and disadvantages. Q1.4 Q1.5 What is DNS? How does it work? Why is it important?

Explanation / Answer

Q1.1

Two protocols of Layer 4 (Transport Layer) are:

1) TCP(Transmission Control Protocol): It ensure reliable end to end delivery of packets.It guarantees that data will be delivered without errors.

2) UDP(User Datagram Protocol) : It provides unreliable delivery of packets.It doesn't guarantee that data will be delivered without errors.

Difference between two:

1) Connection Oriented vs Connection Less: TCP is connection oriented means it establish connection before delivery of packets. But UDP is connection less.

2) Reliability: TCP is reliable it ensures guaranteed delivery of packets. But UDP is not reliable.

Q1.2

Packet Switch: It is node in network which implements packet switching paradigm for data communications. In packet switching data is broken down into small packets and sent to the destination.

Circuit Switch: Circuit switching is paradigm of data communication in which all data packets travels same route,which is determined before data delivery.

Message Switch: This method was used before packet switching.It routes entire message without breaking it down towards destination hop by hop. It uses store and forward mechanism.

Examples of packet switched network:

a)Internet :Internet is network of nodes (computers).

b)Local Area Network .Local area network is small network within an area.

Q1.3

Processing Delay: It is time required to process a packet by node. Which includes checking for errors,determining destination address.

Queueing Delay: It is time for which a packet wait in the queue to get processes by the node of the network.

Transmission Delay: It is time taken by node to push all bits of packet to wire.

Propagation Delay: It is time taken by packets to reach destination.It is sum of all delays in the network.

Traffic intensity greater than 1 means bits arrival rate is more than transmission rate,which will increase queuing delay unbound. To handle the average traffic traffic intensity should be upto 1.

  

Q1.4

A computer can be connected to internet by following ways:

a) Dial Up: it uses phone lines to connect to internet. It is analog communication.

b) Wireless Connection: It doesn't require wire connection between computer and ISPs.

c) Mobile Internet: ISP provides mobile internet.which can be used to connect computers