Unit 1Networks Workbook

What is a computer network?

What is a computer network?

A network is a group of computer and other devices connected together.

Activities

Share files and data

Share printers

Communication (email, social media etc)

Streaming content (videos, TV music)

Storing data (cloud computing)

Accessing the internet

Create a list of the activities computer

networks make possible.

Types of Network

Type of Network Description Example

Wide Area Network (WAN)

Connect computers over a large area such as a town, city or country.

The internet (a global computer network)

Local Area Network (LAN)

Connect computers over a building or a site. School network

Personal Area Network (PAN)

Connect computers or devices used by one person.

Bluetooth headset connected to a mobile phone

Identify the network type from the description.

Bus Topology

Bus topology diagram

Advantages:Easy to install and doesn’t require much cabling.

Disadvantages:If the main cable fails the entire network will go down.

Describe the bus topology

Single main cable to which computers are connected.

Ring Topology

Ring topology diagram

Advantages:Better performance than bus topology.

Disadvantages:A failure in any cable or device can take down the entire network.

Describe the bus topology

All computers are connected in a circle.

Star Topology

Star topology diagram

Advantages:A failure in one cable will only take down one computer’s network access.

Disadvantages:Requires more cable.

Describe the bus topology

All computers have their own link to a central computer.

Mesh Topology

Mesh topology diagram

Advantages:Even if one cable fails there is always an alternative.

Disadvantages:High cost and difficult setup.

Describe the bus topology

Where each computer can connect to other computers.

Network Media

Type RangeTransmission Speed

Security (Good, Medium, Poor)

Copper Cable Up to 500m 1000 Mbps Medium

Fibre Optic Cable

Up to 10,000m 100 Gbps Good

Wireless Up to 250m 600 Mbps Poor

Use internet research to complete the table below:

Transmission Speed

Data transmission speeds are measured in:

Bits per second (bps).

Data storage is measured in:

Bits per second (bps).

The formula used to calculate how long it will take to transfer a file:

Time = size of file (bits) / network speed (bits)

Transmission Time

Scenario Answer (including working)

File Size: 2 KB Speed: 5 Mbps

File Size: 16384 bits

Speed: 5,000,000 bps

Time = 0.0032768

File Size: 3 KB Speed: 1 Mbps

File Size: 24576 bits

Speed: 1,000,000 bps

Time = 0.024576

File Size: 10 KB Speed: 2 Mbps

File Size: 81920 bits

Speed: 2,000,000 bps

Time = 0.04096

Calculate the transmission times for the following scenarios:

Transmission Time

Scenario Answer (including working)

File Size: 1 KB Speed: 10 Mbps

File Size: 8192 bits

Speed: 10,000,000 bps

Time = 0.0008192

File Size: 1 MB Speed: 4 Mbps

File Size: 8388608 bits

Speed: 4,000,000 bps

Time = 2.097152

File Size: 8 KB Speed: 1 Gbps

File Size: 65536 bits

Speed: 1,000,000,000 bps

Time = 0.000065536

Calculate the transmission times for the following scenarios:

Error Detection

Keyword Description

Checksum

A checksum is an algorithm used to check for errors in data transmission. It works by calculating a numerical value based on the number of bits in a packed of data. This value is attached to the packet.

When the packet reaches its destination, the same checksum algorithm is applied to the data. If the two checksums don’t match it shows that an error has occurred and the receiving computer asks the sending computer to re-send that package.

Identify the keyword from the description.

Parity Checking

What is parity checking?

Parity checking is a simple form of error detection. A parity bit is added to the end of a string of binary code to indicate whether the number of bits in the string with the value 1 is even or odd. There are two type of parity bits:

What is even parity?

Where the bit is set to 1 if the number of bits is odd. The extra parity bit will make the number of 1s even.

What is odd parity

Where the parity bit is set to 1 if the number of bits is even. The extra parity bit will make the number of 1s odd.

Parity Checking

Add an even and an odd parity bit to each of these numbers.

Data being transmitted Even parity Odd parity

1011010 10110100 10110101

0110111 01101111 01101110

1100000 11000000 11000001

0101111 01011110 01011111

Network Addressing

What is a MAC address?

A MAC address is a unique number written into the network card, composed of six pairs of hexadecimal characters.

What is a hostname?

A host name is a human-readable label that is assigned to a network device.

Give an example of a MAC address

00:10:5A:44:12:B5