Networks - Introduction

Question 1

What is a network?

Answer 1

A collection of connected computers and devices, with the ability to transmit data between each other.

Question 2

What are the devices in a network known as?

Answer 2

Nodes.

Question 3

What kinds of devices can nodes be?

Answer 3

• Usually computers
• Printers
• Scanners
• Secondary storage devices

Question 4

What must each device connect to a network via?

Answer 4

NIC (or equivalent circuitry built into the motherboard)

Question 5

Why are networks incredibly common now?

Answer 5

Due to the desire to share data and communicate efficiently.

Question 6

What are the advantages of using a private network?

Answer 6

It gives complete control to the owner, including:
• Security (including data access rights)
• Software provision
• Availability of the service.

Question 7

What are disadvantages of using a private network?

Answer 7

Requires a team of specialist staff (especially for large networks) to maintain it as well as ensure its security.

Question 8

What is system redundancy?

Answer 8

Essential equipment is duplicated in the event of a hardware failure.

Question 9

Why are regular backups made on private networks?

Answer 9

Regular backups ensure a copy of stored data is always available.

Question 10

What is a Network Interface Card/Controller?

Answer 10

A circuit that uses ethernet connections in order to transmit and receive data.

These are typically built directly into the motherboards of modern day computers.

Question 11

What is a MAC address?

Answer 11

48-bit identifiers, usually quoted in 6 pairs of hexadecimal numbers.

Question 12

What does the first three octets in a MAC address do?

What about the rest?

Answer 12

Identify the manufacturer of the equipment.

The rest are allocated in a unique method.

Question 13

What do Wireless Access Points do? (WAP)

Answer 13

They enable devices to connect to a network temporarily.

Question 14

From how far away can connections be made?

What concerns does this raise, and what measures are in place?

Answer 14

From approximately 100 metres away.
This causes concern over signal interception.

Methods employed to try circumvent attack include:

• Hiding the SSID
• Encryption
• Limited Access (only accept certain MACs)

Question 15

What does the SSID do?

What does hiding it result in?

Answer 15

The service set identifier (SSID) identifies a wireless access point.

Hiding it prevents being seen by other users.

Question 16

How can signals sent between the router and device be encrypted?

Answer 16

Using various standards such as WPA or WPA2/PSK (WiFi protected access), which uses single use cryptographic keys.

Question 17

In what quantity does the NIC send out signals in?

Answer 17

Packets.

Question 18

What is a hub?

Answer 18

A hardware device that connects multiple devices in a network. All traffic has to pass through the hub.

Question 19

How many hubs can you connect together on large networks?

Answer 19

Two or more.

Question 20

What happens when a hub receives a packet of data?

Answer 20

It re-broadcasts it to every other connected device, ensuring the data gets to where it needs to go.

Question 21

Why is using a hub on a larger network inefficient?

How is this issue overcome?

Answer 21

Network cables can only carry one signal at a time. As the hub continues sending out redundant data packets, data collisions begin to occur. This affects network performance.

This is overcome by using a switch instead of a hub.

Question 22

How are hubs and switches similar?

Answer 22

They both physically join network segments together.

Question 23

How does a switch work?

Answer 23

It has a number of ports and stores the addresses of all network devices that are directly/indirectly connected to it on each port.

As a data packet comes in, its destination address is examined and a direct connection is made between the sending and receiving devices.

Question 24

What is a bridge?

Answer 24

A hardware device that joins two LANs together using the same protocols.

Question 25

What about packets do bridges examine?

Answer 25

It examines the destination IP address of each packet.

Question 26

On a bridge, if the packet is part of the same LAN where it came from, what happens?

Answer 26

It is passed through.

Question 27

On a bridge, if the packet is not part of the same LAN where it came from, what happens?

Answer 27

It is ‘bridged’ across to that network. It is not re-broadcast on the local LAN where it originated from.

Question 28

What is a router?

Answer 28

A hardware device that is connected to many networks.

Question 29

How do routers deal with data packets?

How does it perform this?

Answer 29

It determines the best path through which to send a data packet to the destination node.

It does this by using an internal ‘look up’ table that keeps track of every connection it has available.

Question 30

Routers receive data packets from one network, and using the _______ provided by the packet, it ________ the packet on towards the correct _______.

Answer 30

Routers receive data packets from one network, and using the ADDRESS provided by the packet, it FORWARDS the packet on towards the correct NETWORK.

Question 31

How would routers work together?

Answer 31

Each router knows which other routers are closest to it, and by sharing information, it allows the optimum route for a packet to be calculated.

Question 32

Where are smaller routers used?

Answer 32

In homes to connect computers to the ISP

Question 33

What kinds of routers do large organisations, and those who run the infrastructure of the internet, use?

Answer 33

Very powerful and high speed routers which direct traffic accordingly.

Question 34

For who would a centralised location for data storage be ideal for?

Answer 34

For users who all need access to the same data.

Question 35

What do bridges make the joined networks look like in terms of data packets?

Answer 35

In terms of data packets, it looks like one single, large network.