Chapter 1: Introduction

Question 1

Data communication depends on what four characteristics?

Answer 1

1. Delivery
2. Accuracy
3. Timeliness
4. Jitter

Question 2

What does Delivery mean?

Answer 2

That data is delivered to the intended device, and ONLY to that intended device.

Question 3

What does Accuracy mean?

Answer 3

That data is delivered as it was intended.

Question 4

What does Timeliness mean?

Answer 4

That data is delivered at the correct time and without significant delay.

Question 5

What does Jitter mean?

Answer 5

That data is sent AND received at same rate.

Question 6

What are the five components of data communication?

Answer 6

1. Message
2. Sender
3. Receiver
4. Medium
5. Protocol

Question 7

What are the three types of Data Flow systems?

Answer 7

1. Simplex
2. Half-Duplex
3. Full-Duplex

Question 8

What is Simplex?

Answer 8

A data flow system in which data is sent in only one direction, from sender to receiver. The channel’s entire capacity is used to transmit data.

Exs: monitor, keyboard.

Question 9

What is Half-Duplex?

Answer 9

A data flow system in which data flows bidirectionally but NOT simultaneously. The channel’s entire capacity is used to transmit data.

Ex: walkie-talkies.

Question 10

What is Full-Duplex?

Answer 10

A data flow system in which data flows bidirectionally AND simultaneously. The channel’s capacity is divided into send and receive streams.

Ex: telephone systems.

Question 11

What are the three criteria that a successful network must have?

Answer 11

1. Performance
2. Reliability
3. Security

Question 12

How is network Performance primarily measured?

Answer 12

Throughput: the amount of data that goes through a network in a given amount of time. Usually measured in bits-per-second.

Delay / Latency: the amount of time it takes data to travel from sender to receiver.

Question 13

How is network Security primarily measured?

Answer 13

1. Protecting data from unauthorized access.
2. Protecting data from damage.
3. Policies and procedures for recovering from data breaches and losses.

Question 14

How is network Reliability primarily measured?

Answer 14

1. Frequency of failure.
2. Time to recover from failure.
3. Network robustness during catastrophe.

Question 15

What are the four network topologies?

Answer 15

1. Mesh
2. Star
3. Bus
4. Ring

Question 16

What is a Mesh Topology? Advantages and disadvantages?

Answer 16

Every device on network has dedicated connection to every other device.

Advantages: secure, robust, reliable, and fast.

Disadvantages: difficult to expand, lots of cabling, expensive.

Question 17

What is a Star Topology? What are its advantages and disadvantages?

Answer 17

All devices are connected to a central hub, which mediates data flow.

Advantages: only one I/O port per machine, robust, easy to add and remove nodes, easy to identify problems.

Disadvantages: single point of failure.

Question 18

What is a Bus Topology? What are its advantages and disadvantages?

Answer 18

There is one cable, called the backbone, to which all other devices are connected via a drop line and tap.

Advantages: little cabling, easy to installation.

Disadvantages: Difficult to add new devices, difficult to pinpoint where failure occurs, taps can affect signal quality, backbone is single point of failure.