1.3 - Computer networks, connections and protocols Flashcards
1
Q
What does LAN stand for?
A
Local Area Network
2
Q
What is a LAN?
A
- Covers a small geographical area
- All hardware is owned by the organisation that uses it
- Either wired or wireless
3
Q
Where would you often find LANs?
A
- Businesses
- Schools / Universities
- Homes (connects PCs, TVs, Printers etc)
4
Q
What are some advantages of using a LAN?
A
- Sharing files is easier
- You can share the same hardware
- Internet connection can be shared between every device that is connected
- You can install/update software simultaneously rather than one-by-one
- User accounts can be stored centrally
- You can communicate w/ LAN users cheaply & easily
5
Q
What does WAN stand for?
A
Wide Area Network
6
Q
What is a WAN?
A
- Connects LANs that are in different geographical locations
—> A network that is spread over a large geographical area - They use third party infrastructure
7
Q
How are WANs connected?
A
May be connected using fibre or copper telephone lines, satellite links or radio links
8
Q
Give an example of a WAN:
A
The internet
9
Q
What are the types of Network connection devices?
A
- Hubs
- Switches
- Wireless access points
- Routers
10
Q
What is an NIC?
Where is it found?
A
- Internal piece of hardware
- Allows a device to connect to a network
- Used to be on separate cards but now built into the motherboard
11
Q
What is the purpose of a Switch?
A
Connects devices on a LAN
They receive data from one device & transmit this data to the device on the network (with the correct MAC address)
12
Q
In what units do Switches receive data?
A
Frames
13
Q
What is Routers responsible for?
A
Transmitting data between networks
14
Q
Where are Routers used & why?
A
In homes & offices to connect the LAN to the internet
15
Q
What is the role of Routers on the internet?
A
Directing data (packets) to their destination
16
Q
What are the most common Ethernet cables & what are they?
A
CAT 5e & CAT 6
‘Twisted pair’ cables, contains 4 pairs of copper wires which are twisted together
17
Q
What is the purpose of the ‘4 pairs of copper wires which are twisted together’ in an Ethernet cable?
A
To reduce internal interference
18
Q
What are coaxial cables made of?
A
A single copper wire surrounded by a plastic layer and a metallic mesh
19
Q
What is the purpose of the plastic layer in a Coaxial cable?
A
Insulation
20
Q
What is the purpose of the metallic mesh in a Coaxial cable?
A
Provides shielding from the outside interference
21
Q
What is the purpose of a Fibre Optic Cable?
A
To transmit data as light
22
Q
What are the advantages of a Fibre Optic Cable?
A
- Greater BANDWIDTH = transfer speeds are faster
- Can transmit over VERY LARGE DISTANCES without LOSS OF QUALITY
23
Q
What are the disadvantages of a Fibre Optic Cable?
A
- Very Expensive
24
Q
What is Radio waves used for in a wireless network?
A
To transmit data
25
Name 2 common wireless technologies:
* Wi-Fi
* Bluetooth
26
How are wireless networks more *convenient* than wired networks?
* As you can move around while still being connected
* Cheaper - needs fewer wires
27
Describe what is **Bluetooth**?
* Direct connection between 2 devices so data can be shared
* Low bandwidth compared to Wi-Fi
28
What is the typical connection range for **Bluetooth**?
Connection range varies but its usually **10 metres**
29
Where is **Bluetooth** often used?
Often used in mobile/ wearable devices (headphones, smartwatches etc)
30
Describe what is **Wi-Fi**?
* Can connect multiple devices to a LAN at the same time
* High bandwidth compared to Bluetooth
31
What is the typical connection range for **Wi-Fi**?
**40 - 100 metres**
32
Where is **Wi-Fi** often used?
Homes (Routers, Desktops, Laptops etc)
33
What does a **WAP** stand for?
Wireless access point
34
What is a **WAP**?
A device that connects computers to a network using Wi-Fi.
| Similar to a switch
35
What do devices need to connect to a *WIFI*?
A wireless NIC
| Often built into the device
36
What can you use if you don't have a NIC?
A dongle
37
What are the types of *Dongles*?
* USB dongles
* HDMI dongles
38
What is the purpose of a **USB** dongle?
Can be plugged into computers to allow them to connect wirelessly to the internet
39
What is the purpose of a **HDMI** dongle?
Can use wireless networks to stream high-quality video to a TV
40
What factors affect network performance?
* Number of devices on the network
* The bandwidth of the
transmission medium
* Type of network traffic
* Network latency
* The number of transmission errors
* Network topology
41
What is **Bandwidth**?
Measures the amount of data that can transfer through a communications channel over a given period of time
42
What happens to a *network* if the bandwidth is *high*?
The network can preform better
43
What is *available bandwidth* shared between on a network?
The devices on a network
44
What happens to a network when there are too many devices or heavy use of it?
May cause congestion & slow the network
45
How can you *fix* network congestion/ heavy use?
Limit the bandwidth available to individual users
46
# Wired or wireless?
What type of connection is faster & more reliable?
Wired
47
What type of cable gives better performance?
Fibre optic
| Rather than copper
48
What does *wireless performance* depend on?
Signal quality
49
What is *wireless performance* affected by?
* Range of the device
* Amount of interference from other wireless networks
* Physical obstructions (e.g. Thick walls from buildings)
50
What *manages* the client-server network?
A server
51
What are the devices that are connected to the server called?
| In a client-server network
Clients
52
What type of organisations would be best suited for *client-server* networks?
* Organisations with many computers
* Situations where many computers need access to the same information
53
Give an example of a type of organisation that would use *client-server* networks:
Schools
54
What is a **server**?
A computer that manages and stores files
55
What are the **advantages** of *client-server* networks?
* Easy to keep track of files
* Easier to preform backups
* Easy to install & update software
* Easy to manage network security
* Reliable & always on
56
Why is it 'easy to keep track of files' in a *client-server* networks?
They are stored centrally
57
What are the **disadvantages** of *client-server* networks?
* Expensive to set up
* Needs IT specialists to maintain network & server
* Server dependence
* May become overloaded if too many people are accessing it at once
58
Why is 'Server dependence' a risk in a client-server network?
If the server goes down all clients lose access to their work
59
What are the **advantages** of *peer-to-peer* networks?
* Easy to maintain
* No dependence on server
60
Why are *peer-to-peer* networks **easy to maintain**?
As you don't need any expertise or expensive hardware
61
Why is **server dependence** in a *peer-to-peer* networks an advantage?
If one device fails the whole network isn't lost
62
What are the **disadvantages** of *peer-to-peer* networks?
* No centralised management
* Machines are prone to slow down when other devices access them
* Less reliable: data may be lost if one fails
* Copying files between devices creates duplicate files
63
Why is **no centralised management** in a *peer-to-peer* networks a disadvantage?
* Devices need updates and security installed individually
* Backups are more complicated
64
Where might you use a *peer-to-peer* network?
At home to share files between devices or connect devices to a printer
65
Name some **server types**
* File server
* Web server
* Print server
* Applications server
* Mail server
66
What is a **file server**?
Hold and maintain user files
67
What is a **web server**?
Hold and share web pages
68
What is a **print server**?
Manage printing across a network
69
What is a **mail server**?
Handle emails between users
70
What is a **applications server**?
Allows programs to be run over a network
71
What is a **star topology**?
A network where each node is connected to a central switch
72
What are some **advantages** of the **star topology**?
* If a device fails / cable is disconnected - rest of network unaffected
* Simple to add more devices to the network
* Better performance than other setups
73
What are some **disadvantages** of the **star topology**?
* Expensive = every device needs a cable to connect to the central switch or server
* If there is a problem w/ the switch - whole network is affected
74
How does the **star topology** have **better performance** than *other setups*?
Data flows in one direction (unlike bus network) & all devices can transmit data @ once (unlike ring network)
75
What is a **bus network**?
All devices are arranged in a line, connected to a single backbone cable
76
What is a **disadvantage** of the **bus network**?
Devices send data in both directions = causes data collisions
77
What is a **ring network**?
Data moves in one direction around the ring, preventing data collisions
78
What is a **disadvantage** of the **ring network**?
One device can send data at a time & data passes through many devices before its destination
79
What is a **mesh topology**?
All devices are connected to each other
80
How do **mesh networks** work?
By sending data along the fastest route from one device to another
81
What are some **advantages** of the **mesh topology**?
No single point where the network can fail
82
Explain how there is *No single point where the network can fail* in a **mesh topology**?
If one device fails, then the data is sent along a different route to get to its target
83
What are some **disadvantages** of the **mesh topology**?
Very expensive = needs a lot of wires to connect devices together
84
What's the *difference* between a **full mesh and a partial mesh topology**?
Full mesh = Every device is connected to every other device
Partial mesh = Not all devices are fully connected
85
What does **HTTP** stand for?
Hyper text transfer protocol
86
What is **HTTP** used for?
Used by web browsers to access websites and communicate with web servers
87
What does **HTTPS** stand for?
Hyper text transfer protocol - secure
88
What is **HTTPS** used for?
* More secure version of HTTP
* Encrypts all information send and received
89
What does **FTP** stand for?
File transfer protocol
90
What is **FTP** used for?
Used to access, edit & move files between devices on a network
91
What does **POP3** stand for?
Post office protocol (version 3)
92
What is **POP3** used for?
Used to retrieve emails from a server
---> Holds email until YOU download it (then it is deleted)
93
What does **IMAP** stand for?
Internet message access protocol
94
What is **IMAP** used for?
Used to retrieve emails from a server
---> Holds emails until YOU delete it (you only download a copy)
95
Which *protocol* is used by most **web-based email clients**?
IMAP
96
What does **SMTP** stand for?
Simple mail transfer protocol
97
What is **SMTP** used for?
* Used to send emails
* Also used to transfer emails between servers
98
What does **TCP** stand for?
Transmission control protocol
99
What's **TCP** used for?
* Sets the rules for how devices connect on a network
* Splits data into packets & reassembles at the destination
* Checks data is correctly sent & delivered
100
What does **IP** stand for?
Internet protocol
101
What's **IP** used for?
Directing packets to their destination across a network
102
What is a **layer**?
A group of protocols which have similar functions
A division of network functionality
103
Give some *characteristics* of **layers**
* Self-contained
* Each layer serves the layer above it
* Data can only be passed through adjacent layers
104
What are the **advantages** of *layers*?
* Breaks network communication into manageable pieces
* Self contained
* There are standards for each layer
105
How is **having standards** for **layers** an **advantage**?
Forces companies to make compatible, universal hard/software - different brand will work w/ each other
106
How is **breaks network communications into manageable pieces** an **advantage** for **layers** ?
Helps developers to concentrate only on 1 area without having to worry about the others
107
How is **layer's being self contained** an **advantage**?
They can be changed without the other layers being affected
108
What is **Hosting**?
When a business uses servers to store files of another organisation
109
What is **cloud computing**?
When clients access data storage, software & processing power remotely over the internet
110
What are the **advantages** of **the cloud**?
* Users can access files & applications from any connected device
* Easy to increase how much storage is available
* Automatic updates
* No need to but expensive hardware
111
What are the **disadvantages** of **the cloud**?
* Needs connection to the internet
* Dependant on the host for security & backups
* Subscription fees for using cloud storage & software can be expensive
* Data can be vulnerable to hackers
112
What are **URLs**?
Addresses used to access web servers & resources on them
113
What is a **DNS** used for?
To translate website domain names into IP addresses
114
What does a **DNS server** store?
A list of domain names & a list of corresponding IP addresses where the website is stored
115
Describe the steps taken to **display a webpage**
1) Domain name is typed into the address bar of the browser
2) A query is sent to the local DNS server for the corresponding IP address if that domain name
3) Local DNS server will check if it holds that info. If it does, it'll pass the IP address to the browser
4) Browser connects to the IP address of the server & accesses the website
116
What will happen if the **local DNS server** does not **hold the IP address**?
The query is passed to another DNS server at a higher level until the IP address is resolved
117
What is the **internet**?
A global network of interconnected networks
118
What is the *purpose* of a **web server**?
Processes the client request to prepare the webpage & return it so the web browser can display it to the user
119
What is a **domain registrar**?
A company that checks the domain name is valid and not already taken
120
What are **networking standards**?
Rules that allow computer systems to communicate across networks
121
Why have **networking standards** been created?
To ensure devices can exchange data & work together
122
What is the **TCP/IP** model used for?
To visualise the different parts of a network as each layer has specific roles
123
How many **layers** are there in the **TCP/IP** model?
4
124
Why is **splitting a network design into layers** beneficial?
As it simplifies design - making it easier to modify & use
125
What is the **purpose** of the **data link layer**?
Handles the transmission errors & passes data to the physical layer
126
What **layer number** is the **data link layer**?
1
127
Which **protocols** are in the **data link layer**?
Ethernet
128
What is the **purpose** of the **internet layer**?
Finds the optimal route for the data to take is calculated
129
What **layer number** is the **internet layer**?
2
130
Which **protocols** are in the **internet layer**?
IP
131
What is the **purpose** of the **transport layer**?
Makes sure the data is sent & received in the correct order & reassembled at the destination without errors
132
What **layer number** is the **transport layer**?
3
133
Which **protocols** are in the **transport layer**?
TCP
134
What is the **purpose** of the **application layer**?
Allows humans & software applications to use the network
135
What **layer number** is the **application layer**?
4
136
Which **protocols** are in the **application layer**?
* HTTP
* HTTPs
* SMTP
* FTP
