3.5 Networks - full Flashcards
Only need to use this for networks
1
Q
Node?
A
Any device connected to a network.
2
Q
Network topology ?
- incl 2 examples
A
the arrangement, or pattern, in which all nodes on a network are connected together. There are several common topologies that are in use, but today the most common topologies are:
bus topologies
star topologies
3
Q
Define network
A
A network is two or more computers - or other electronic devices - that are connected together for the purpose of communication.
4
Q
How are computers connected
A
They are connected by a wired medium such as cables, or by a wireless medium such as Wi-Fi.
5
Q
Stand-alone
A
A computer or device that is not connected to a network is called a stand-alone.
6
Q
Today, many different types of computer are connected to some form of network. As well as PCs, many other devices such as
A
Today, many different types of computer are connected to some form of network. As well as PCs, many other devices such as smartphones, smartwatches, fitness trackers, car engine management systems, internet-enabled fridges, intelligent personal assistants and media boxes can all be connected.
7
Q
There are three classifications of network:
A
local area networks (LANs)
wide area networks (WANs)
personal area networks (PANs)
8
Q
LAN - spec (2)
A
- usually cover relatively small geographical areas
- often owned and controlled/managed by a single person or organisation
9
Q
So what’s a LAN and give examples (6)
A
A local area network (LAN) is a network that is geographically confined to one building or site. Examples include networks employed by small businesses, small organisations, schools, colleges, universities and in homes.
10
Q
WAN - spec (3), incl what’s the biggest
A
- the Internet is the biggest example of a WAN
- WANs usually cover a wide geographical area
- WANs are often under collective or distributed ownership
11
Q
So what’s a LAN?
What can it cover?
Examples + why/how?
A
A wide area network (WAN) is a network that is spread over a wide geographical area. It can cover more than one site, or be spread across a country, or even the world.
Organisations that have more than one office or branch, such as banks, tend to use a WAN. The WAN allows the head office to communicate and share data with the sub-offices and branches. Communication is through national telephone infrastructures or via wireless transmission. While each office or branch has its own LAN, they are connected together using the WAN.
The internet is essentially a huge, international WAN.
12
Q
PAN - define (2) + examples (3)
A
A personal area network (PAN) is a network that is spread over a very small area. It often covers no more than a few metres and is used to connect personal devices such as a smartphone and wireless headphones or a laptop.
13
Q
Setting up a PAN using a smartphone is also known as creating a ‘__’ and makes use of limited __ or __ to connect devices.
A
Setting up a PAN using a smartphone is also known as creating a ‘hotspot’ and makes use of limited Wi-Fi or bluetooth to connect devices.
14
Q
PAN spec - only what needs to be considered?
A
Bluetooth
15
Q
To connect a computer or device to a network, several hardware components are required: (3)
A
- a network interface controller (NIC) or wireless network interface controller
- a transmission medium, either wired or wireless
- a point to connect to, such as a router, hub, switch or wireless access point (WAP)
16
Q
What does transmission media do?
A
Transmission media carry data signals from one computer to another.
17
Q
What a network interface card?
And a wireless NIC?
A
A network interface card (NIC) offers an interface port for a wired connection. A wireless NIC provides a radio transceiver for connecting wirelessly.
18
Q
NICs in different types of devices:
- modern PCs
- mobile devices
A
Most modern PCs come with a NIC and wireless NIC built-in, providing the option of either connection method. However, mobile devices such as tablets, smartphones and many embedded devices only feature a wireless NIC, giving only wireless connection.
19
Q
What does a network connection device do?
A
A network connection device allows computers to connect to a network.
20
Q
2 types of network connection devices
A
- switches
- routers
21
Q
Switches
- what
- how work
- and therefore, good because
A
- Switches are network devices that record which computers are connected to which ports.
- When traffic is received, the switch forwards the traffic to its intended recipient only.
- This improves network performance by cutting down on unnecessary transmissions from older style networks.
22
Q
Routers
- what is they
- what they used for
A
- Routers are one of the most commonly used connection devices.
- They are used to send data signals across the internet.
23
Q
How do routers work? (2)
A
- Routers work by collecting knowledge of available routes to transmit data.
- They then determine the most suitable route for sending data.
24
Q
Routers in homes:
- additional hardware (2)
A
Routers are also commonly used in homes.
- These types of router usually contain additional hardware that allows a network to be formed.
- Additionally, they contain a modem, which allows users to connect to the internet.
25
Define modem
Meaning 'modulator/demodulator'. Allows computers to connect to a network over a telephone line.
26
What transmission media do?
| Two types?
- Transmission media carry data signals from one computer to another.
- Media are either wired or wireless.
27
In modern networks, wired media use either (2)
In modern networks, wired media use either twisted copper wiring, or fibre-optic cable.
28
Compare Twisted copper wire with Fibre-optic cable:
- cost
TCW:
- Cheaper to purchase and install
F-O C:
- More expensive to purchase and install
29
Compare Twisted copper wire with Fibre-optic cable:
- maximum transmission speed
TCW:
- Up to 1 gigabit per second
F-O C:
- Over 40 terabits per second
30
Compare Twisted copper wire with Fibre-optic cable:
- maximum distance for reliable connection
TCW:
- Up to 100 metres
F-O C:
- Over 2 kilometres
31
WAP
| - what it does, using what
A wireless access point (WAP) uses a radio transceiver to allow wireless connections to a network.
32
So how a WAP actually works (3)
- A wireless access point (WAP) uses a radio transceiver to allow wireless connections to a network.
- In effect, the WAP creates its own wireless network, which devices connect to.
- The WAP then sends the wireless traffic it receives on to the main wired network.
33
Another use of WAPs + 2 examples
- WAPs can also be used to extend the range of a wireless network.
- In this case, the WAP can either receive or transmit traffic to other WAPs, or it can be connected via a cable to the main network.
34
Where ethernet (copper) uses ___, fibre optic cables transfer data using __.
Where ethernet uses electrical signals, fibre optic cables transfer data using light.
35
The main adv of fibre optic
| - also how are they limited
Fibre optic cables offers extremely high bandwidth (they can transfer a lot of data in a given time). So much bandwidth, in fact, that fibre optic networks are usually limited by the equipment connected to the cable rather than the cable itself.
36
what is a transceiver
A device that transmits and receives messages.
37
Wired networks:
- how identified
- most often used
- Wired networks are identified by their use of physical wiring to connect devices.
- They are most often used for office networks or for devices that are unlikely to move as the cables limit the ability to move away from the connection point.
38
Wireless networks:
- how do they carry signals
- tell me about these signals (2)
- Wireless networks use radio waves to carry signals.
- These signals are limited in range - usually up to 50 metres - but are subject to interference.
- They can also be blocked by walls.
39
What is a wireless network ideal for and why?
they are ideal for mobile devices as a device can connect to a network as long as it is in the range of a wireless access point (WAP).
40
Wired vs wireless networks:
Cost
It is more costly than Wi-Fi to install in a building
Only needs a Wireless Access Point to set up, so is cheaper.
41
Wired vs wireless networks:
Connections
Can only allow a limited number of people to connect at any one time
Allows hundreds of people to log in at the same time.
42
Wired vs wireless networks:
Interference
It is immune to radio interference
Affected by radio interference
43
Wired vs wireless networks:
Bandwidth
High bandwidth, more than 10 Gbps is common
Lower bandwidth 54Mbps
44
Wired vs wireless networks:
Security
Excellent security as a computer needs to be physically connected to the network
Not so secure. Radio waves can be picked up by anyone. So the WAP needs a strong password and encryption to disguise data being transmitted
45
Wired vs wireless networks:
Physical layout
Not affected by building layout
Signal is affected by walls and floors
46
Wired vs wireless networks:
| Portability
Not portable as each computer needs to have a network socket available.
Very mobile, an user can carry their laptop from office to office and not lose a connection.
47
Define network protocol (2)
A set of rules that allow two devices to communicate
48
The protocol used for communicating over the internet is
The protocol used for communicating over the internet is called TCP/IP, or "Transmission Control Protocol / Internet Protocol".
It has two parts: TCP and IP.
49
TCP - what does this protocol govern
TCP - Transmission Control Protocol
This protocol governs how messages are prepared for transmission, and how computers that receive a message from the Internet will put the message back together
50
When sending data the TCP rules (protocol) include
| 3
- Dividing the message into chunks called "packets"
- Adding a sequence number to each packet so the message can be re-assembled
- Adding extra error-correction information, so errors can be spotted and fixed
51
When receiving data the TCP rules (protocol) include (4)
- Examining each packet for errors by using the extra information that was added to it
- Fixing any errors (if possible) or requesting that the packet be re-sent
- Spotting missing packets and requesting them to be re-sent
- If all packets are present, using the sequence number of each packet to re-assemble the message
52
IP - this protocol is responsible for what + when
IP - Internet Protocol
When transmitting messages, this protocol is responsible for providing the destination address and to recognise incoming data packets.
53
For sending data the IP rules (protocol) include (2)
- Add the destination address to each data packet
| - Add it own address to indicate where it came from
54
For receiving data packets the IP rules (protocol) include
| 2
- Accept data packets that have its own address attached
| - Ignore all data packets that do not contain its own address
55
What is UDP (3)
The User Datagram Protocol (UDP) is an alternative to TCP.
We just mentioned how TCP spots missing packets and requests that they be re-sent. UDP doesn't do that.
Instead, messages sent using UDP are sent without any error correction bits. The sender just assumes that they will all arrive error-free.
56
Advantage of UDP
| Disadvantage of UDP
The advantage of UDP is that since it doesn't have this back-and-forth of asking for corrupted packages to be re-sent (a process called 'handshaking'), it transfers messages much faster. The downside is that when errors do appear, they aren't fixed.
57
When UDP used
| - with examples (2)
UDP is well-suited to roles such as video conferencing and real-time online computer games, where a fast connection is more important than a few dropped packages. This is part of why, when you look at a live video stream online, there are far more video artifacts and glitches than if you watch a video saved on your hard disk.
58
HTTP use
HTTP, or "HyperText Transfer Protocol", is the protocol underlying the World Wide Web.
Web pages are sent and received using the http protocol.
59
How http protocol works (3)
- A web page is made up of a collection of individual files - text, images, styling, javascript and so on.
- The http protocol allows a browser to request these individual files from a web server in an orderly way.
- Once received, they are rendered into a web page such as the one you are reading at the moment.
60
How to see if website uses https protocol
A web page that begins with https:// is using this protocol.
61
HTTPS - meaning
There is a variation of http, called 'https' (extra s on the end), meaning 'http secure'
62
tell me about https
This protocol works like http, but also encrypts web page data before it is sent out of the browser or server, to make sure that nobody can intercept the data and read it themselves.
For example, if you are viewing a typical login page that starts with https:// the browser encrypts the user name and password before it is sent to the server. Only the server can decrypt the details.
63
FTP = used to
FTP, or 'File Transfer Protocol' is a standard network protocol used to transfer (i.e. upload and download) files between a regular computer and a server on a computer network.
64
Watch a video on these protocols imo.
Ok
65
3 email protocol
| Which two are on spec
POP, SMTP, IMAP
| SMTP, IMAP
66
POP - purpose
There are several different protocols for sending and receiving e-mails. Post Office Protocol (POP) is one of the simplest. It allows emails to be downloaded and /or deleted from a mail server and viewed offline by an email client.
67
3 disadvantages of POP
- it can only handle one mailbox
- messages, once downloaded, are removed from the email server and cannot later be viewed by other devices
- it does not support complex searches of emails on the server.
68
IMAP - what does
- Internet Message Access Protocol (IMAP) is similar in many ways to POP but it also offers more complex commands to manage emails on the server itself.
- Unlike POP the email remains on the server even after being downloaded to the device. This means that you can use multiple devices and perhaps view your emails using your laptop and then access them from elsewhere on your smartphone and they will still look exactly the same.
69
IMAP allows (5)
- Set flags on emails showing whether they have been viewed (read), replied to, deleted etc
- Access emails on multiple devices i.e. PC, smart phone, tablet etc
- It allows complex searches to be carried out based on subject, headers and so on.
- It can handle more than one mail box.
- You can choose whether to download just the headers, full body or not to download attachments.
70
SMTP - use
Simple Mail Transport Protocol (SMTP) is used by the mail server itself to send and receive emails from all other mail servers across the internet.
71
So what transfers mail from mail server to email client
POP or IMAP
72
So what transfers mail from mail server to another mail server
SMTP
73
DEFINE Ethernet (2)
- Ethernet is a family of protocols responsible for sending and receiving data along a network cable.
- Ethernet works over a range of data speeds hence the reason for a family of protocols rather than just one.
74
Ethernet is the most common protocol used for putting together (WHAT)?
Ethernet is the most common protocol used for putting together a local area network (LAN).
75
The Ethernet protocol is in several parts: - 3
- Hardware. Specifies the performance expected of network cables, plugs and sockets.
- Data format. Describes the format of the data packets sent or received over the network.
- How to deal with data collisions i.e. when two devices send data at exactly the same time.
76
When HTTPS used - spec
Provides an encrypted version of HTTP for more secure web transactions
77
Wi-Fi is a __.
| The generic term for networks of this nature is __.
Trademark
| WLAN
78
If you have time, do the network protocols Brainscape, after all this Brainscape is done (or once the network protocol section is done on this Brainscape)
Ok
79
Wi-Fi
a family of protocols for wireless communications
80
WLAN (Wireless Local Area Network) devices use __ technology to form a network
WLAN (Wireless Local Area Network) devices use radio technology to form a network
81
Wi-Fi use (read once and skip)
Wi-Fi is also a family of related protocols and deals with how data is sent through wireless connections. In fact, Wi-Fi is a trademark, and the generic term for networks of this nature is WLAN. Any device which has the Wi-Fi logo on it uses the Wi-Fi protocol, and therefore is able to connect wirelessly to other Wi-Fi enabled devices.
82
What is a layer
A layer is a group of protocols that all serve a similar function.
83
The 4 layer TCP/IP model:
- application layer
- transport layer
- internet layer
- link layer
84
protocols in each layer can communicate with
It is important to remember that the protocols in each layer can only communicate with those in the layers directly above and below it.
85
Application layer (2)
- The layer of protocols dealing with user applications and how data moves in and out of these applications.
- this is where the network applications, such as web browsers or email programs, operate
86
The Application Layer is the __ layer in the Four Layer Model.
The protocols in this layer govern - ?
The Application Layer is the topmost layer in the Four Layer Model. The protocols in this layer govern how data moves in and out of applications.
87
5 protocols that operate at the application layer - and what use each of them
- Web browsers use the HTTP & HTTPS protocols
- Email applications use the POP and SMTP protocols
- Servers use the FTP protocol
88
Protocols in the Application layer interact with?
As mentioned earlier, layers can only 'talk' to adjacent layers. That is, the protocols in the Application layer only interact with the protocols in the Transport layer.
89
Transport layer (2)
- The layer of protocols dealing with the movement of data packets and how devices communicate with one another.
- this layer sets up the communication between the two hosts and they agree settings such as ‘language’ and size of packets
90
Transport layer:
- protocols used when?
- these protocols also agree what
- the layer also handles what
- what the layer interacts with
When two devices (or hosts) want to communicate with one another and transmit data, they will use the protocols in the transport layer.
The protocols also agree the settings to be used throughout the communication such as 'language' i.e. commands, and size of data packets.
The transport layer also handles any error checking.
The transport layer interacts with the application layer above it and the Internet layer below it.
91
2 protocols that operate at the transport layer
TCP, UDP
92
Bbc - the what the transport layer does
this breaks down the message into small chunks (packets). Each packet is given a packet number and the total number of packets. This layer sets up the communication between hosts, using protocols such as TCP and UDP.
93
Network layer is known as what on the spec
Internet layer
94
Internet layer (3)
- The layer of protocols dealing with the structure of data packets.
- addresses and packages data for transmission
- routes the packets across the network
95
What protocol operates at the internet layer
IP
96
Internet/ network layer
| - what it does (bbc b)
this adds the sender’s and recipient’s IP addresses to the packet, and packages the data to make it ready for transmission. The network layer also routes the packets across the network.
97
At the network layer -what the internet protocol does (3)
The Internet Protocol ensures that packets are prepared correctly prior to sending across the network.
This involves including a suitable destination address within each data packet.
The protocol routes the packets across the network.
Once it has arrived, it checks the destination address within each packet.
If it matches its own address then it passes the packet up to the transport layer (layer 3). If it does not match, the packet is ignored.
98
Link layer - alternative names
Data link layer, network interface layer
99
Link layer (3)
- layer of protocols dealing with the transport medium and network hardware
- this is where the network hardware such as the NIC (network interface card) is located.
- OS device drivers also ist here
100
The data link layer - 2 fucntions
This layer in the model is where the network hardware, such as the network interface card (NIC), cables etc are located. Also software, such as the operating system device drivers appear in this layer.
The data link layer is responsible for handling the device's physical connection to the network.
101
2 protocols at link layer
Ethernet, WiFi
102
LAST THING - PURPOSES OF ALL 4 LAYERS - good to know
Ok
103
```
FOUR - PURPOSE
APPLICATION LAYER (1)
```
The protocols in this layer provide access to email, files and websites across an IP network
104
```
THREE - PURPOSE
TRANSPORT LAYER (3)
```
- The TCP part pf the TCP/IP protocol resides in this layer.
- it is responsible for dividing messages into packets, adding sequence numbers and error correction information
- it also checks and deals with errors of received data packets
105
```
TWO - PURPOSE
INTERNET LAYER (2)
```
- The IP part of the TCP/IP protocol resides in this layer
| - it is responsible for managing the dares of source and destination locations
106
```
ONE - PURPOSE
LINK LAYER (1)
```
- the protocols in this layer are responsible for actually transmitting and receiving data through cable or wireless
107
FINALLY
What does layering allow
+ an example
Layering allows standards to be developed, but also to be adapted to new hardware and software over time.
For example, different software packages - applications - may use the same transport, network and link layers but have their own application layer. The way the program encodes the message changes - the rest of the communication method remains the same.
