1.3 Computer Networks, Connections and Protocols Flashcards
1
Q
Network
A
Formed when 2 or more computers are linked together in order to communicate + share resources
2
Q
LAN full form
A
Local Area Network
3
Q
LAN
A
A network covering a small geographical area on a single site
Computers are connected to each other
4
Q
Who is hardware owned by in a LAN?
A
By the organisation
5
Q
Are LANs wired or wireless?
A
Wired (e.g. using ethernet cables) or Wireless (e.g. using Wi-Fi)
6
Q
WAN full form
A
Wide Area Network
7
Q
WAN
A
Connects LANs that are in different geographical locations
8
Q
Example use of a WAN
A
businesses with offices abroad
9
Q
Who is hardware owned by in a WAN?
A
Hire infrastructure
10
Q
Are WANs wired or wireless?
A
Wired
11
Q
What medium do WANs use?
A
Fibre - Optic
Copper telephone lines
Satellite links
Radio links
12
Q
What is the biggest WAN?
A
The Internet
13
Q
Factors that affect Network Performance
A
Bandwidth available
Transmission media
Number of users
Network Topology
Choice of hardware
14
Q
NIC full form
A
Network Interface Controller
15
Q
NIC
A
allow a device to connect to a network. Each one has a unique MAC address
16
Q
Switches
A
Connect devices on a LAN. Receives data in frames from one device and transmits the data to the device with the correct MAC address
17
Q
Routers
A
Transmits data between networks. Directs data in packets to their destination
Recieves data between networks
Forwards data to their destination
18
Q
Where are Routers used?
A
Homes / offices to connect a LAN to the internet
19
Q
3 types of Transmission Media
A
Fibre Optic Cables
Coaxial Cables
Ethernet
20
Q
Fibre Optic Cables
A
- Transmit data as light
- High performance/no interference =
expensive - Can transmit data over long distances
21
Q
Coaxial Cables
A
Single copper wire with plastic insulation and metal mesh (shielding from outside interference)
22
Q
Ethernet
A
Most common: CAT 5e, CAT 6
4 pairs of twisted cables -> to reduce interference
23
Q
Bluetooth
A
Direct connection between 2 devices
24
Q
Bluetooth connection range
A
10m
25
Bluetooth Bandwidth
Low
26
Bluetooth uses
Mobile/wearable devices
27
Wi-FI
For multiple devices to connect to a LAN at the same time
28
Wi-Fi connection range
40-100m
29
Wi-Fi Bandwidth
High
30
Wi-Fi uses
Home
31
Client - Server
Managed by a server
Files + software are stored centrally
32
Client - Server Relationship
Clients send requests to the server to access data
33
What does a client - server server store
Files
Passwords
34
Example of a client-server relationship
Websites are hosted on web – servers. Web browsers (clients) sent requests to the web – servers to access data
35
Advantages of a Client - Server
Easy to keep track of files
Easy to perform backups
Easy to install + update software
36
Disadvantages of a Client - Server
Expensive to setup
Server dependence - if the server is down then all clients lose their work
Server may become overloaded – too many clients access it at once
37
Peer to Peer
All devices are equal –> connect directly to each other
38
Where are files stored on a peer to peer
On individual devices
39
Uses of Peer to Peer
Home to share files between devices/share hardware
40
Advantages of Peer-to-Peer
Easy to maintain – no expensive hardware
No dependence on server – if one device fails the whole network isn’t lost
41
Disadvantages of Peer-to-Peer
No centralised management -> backups + software updates are more complicated
Copying files between devices creates duplicate files which can easily be lost track of
42
Topology
The layout of a network
How the devices are connected together
43
Examples of Network Topologies
Star
Mesh
Partial Mesh
Bus
Ring
44
Star Topology
All the devices are connected to a central switch/server
Wired or wireless
45
What is the central switch for in a star topology
Allows many devices to access the server at the same time
46
Advantages of a Star Topology
If a device fails/cable disconnects, the rest of the network is unaffected
Easier to add devices to the network
Very few data collisions
47
Disadvantages of a Star Topology
In a wired star network, every device needs a cable -> expensive
Centralised -> If the switch is not working, the whole network is affected
48
Mesh Topology
Decentralised – all devices are connected to each other
Send data on the fastest route from one device to another
49
Advantage of Mesh Topology
No single point likely to fail -> if a device fails, data can be sent on another route
50
Disadvantage of Mesh Topology
Wired mesh networks are expensive to set up
51
Partial Mesh Topology
All the devices are not fully – connected to each other
52
Bus Topology
All devices are arranged in a line, connected to a single backbone cable -> lots of data collisions
53
Ring Topology
All data moves in one direction to prevent collisions.
Only one device can send data at a time, and has to pass through many devices before reaching its destination
54
Network Standard
a set of agreed requirements for hardware and software
55
What is the point of network standards?
Allows manufacturers to create products/programs that will be compatible with other products/programs or will work on other systems
56
Network Protocol
A set of rules for how devices communicate + how data is transmitted on a network
57
Communication Protocols
specify how communication between 2 devices must start and end (how data must be organised, what to do if data goes missing)
58
MAC addresses full form
Media Access Control address
59
MAC address
For communication on the same network
Used by ethernet protocols or LANs
60
IP address
For communication between different networks
61
What does every NIC have?
A MAC address
62
When are MAC addresses assigned
On manufacture -> unique, cannot be changed
63
Form of MAC address
48 or 64 bit
Converted to six groups of two hexadecimal -> for ease
64
What do LAN switches use MAC addresses for?
to direct data to the right device on a network
65
What are IP addresses assigned to?
Every device connecting to the internet is assigned an IP address so that it can be identified/located
66
Types of IP address
IPv4
IPv6
67
IPv4
32-bit, 2*32 possibilities
Split into 8–bit chunks, and each chunk is given a denary number
68
IPv6
128 bits, 2*128 possibilities
Split into 16-bit chunks, and each chunk is given a hexadecimal number
69
Why was IPv6 created?
Created due to increasing number of devices needing unique IP addresses
70
HTTP full form
Hyper Text Transfer Protocol
71
HTTP use
Used by web browsers to access websites + communicate with web servers
72
HTTPS full form
Hyper Text Transfer Protocol Secure
73
HTTPS use
More secure version of HTTP. Encrypts all information sent and received
74
FTP full form
File Transfer Protocol
75
FTP use
Used to access, edit and move files between devices on a network
76
POP3 full form
Post Office Protocol version 3
77
POP3 use
Used to retrieve emails from a server. The email is deleted from the server after the client has downloaded it
78
IMAP full form
Internet Message Access Protocol
79
IMAP use
Used to retrieve emails from a server. The email is remains on the server after the client has downloaded it (the client only downloads a copy)
80
SMTP full form
Simple Mail Transfer Protocol
81
SMTP use
Used to send emails + transfer emails between servers
82
TCP/IP
a group of protocols dictating how data should be transmitted between networks
83
TCP full form
Transmission Control Protocol
84
TCP use
How devices should connect to a network
Splits data into packets + reassembles them once they have reached their destination
Check if data is correctly sent + delivered
85
IP full form
Internet Protocol
86
IP use
Directs data to their destination across a network
87
Layer
a division of network functionality
a group of protocols which have similar functions
88
Characteristics of a layer
Self - contained
Data can only be passed between adjacent layers
89
Advantages of Layers
Self - contained -> they can be changed without affecting the other layers
Different people can work on different layers
Easier to identify + correct errors
Forces companies to make compatible/universal hardware + software -> that will work together
90
Internet
a worldwide collection of networks linked together as a WAN. Based around TCP/IP
91
World Wide Web (WWW)
a collection of websites that are hosted on web servers
92
URLs
addresses used to access web servers and resources on them
93
URL full form
Uniform Resource Locator
94
DNS
translates domain names (URLS) into IP addresses. The IP addresses are stored on Domain Name Servers
95
DNS full form
Domain Name Service
96
Hosting
when businesses use its servers to store files of another organisation
97
Cloud computing ('the cloud')
acts as an extension of a client – server network, where user files are stored centrally on a network server
98
Advantages of the Cloud
Users can access files + applications from any device
Easy to increase available storage
No expensive hardware
99
Disadvantages of the Cloud
Needs internet connection to access
Dependent on host’s security -> vulnerable to hackers
Subscription fee
Connection may be slow
100
How does a device open a website
* The website is hosted on webservers
* The website had an IP address
* The web browser sends URL to the DNS
* The DNS finds the matching IP
* If IP is not found, browser sends request to higher DNS
* IP is sent back to the web browser
* The web browser sends a request to the webserver
* The webserver processes the request for the website
* The webserver sends the website to the user
