1.3- Computer Networks, Connections and Protocols Flashcards

1
Q

Packet

A

A small block of data which is transported from one computer to another.

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2
Q

Header

A

The part of the packet which contains the sender and destination addresses, the protocol being used and a packet number.

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3
Q

Payload

A

The part of the packet which contains the actual data which is being sent.

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4
Q

Source address

A

The address of the device where the initial message has been sent from.

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5
Q

Destination address

A

The address of the device where the message is going to.

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6
Q

Handshake

A

An agreement which must be made between two devices, before communicating over the internet.

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7
Q

Application

A

The protocols in this layer determine how the data will be transferred in applications. Web browsers, email clients and file transfer protocols operate here.

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8
Q

Data link

A

The layer where the network hardware is located such as the network interface card and cabling. Ethernet and Wi-Fi run here.

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9
Q

Internet layer

A

This layer routes the packets across the network using the IP protocol

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10
Q

Transport

A

Sets up the communication between the two devices communicating data and breaks the data in to the agreed packet size. TCP and IP run here.

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11
Q

IP address

A

A numerical address assigned to a device communicating data across the internet. This address changes. IPv4 format is 4 bytes, IPv6 uses 16 bytes for more addresses.

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12
Q

Error detection

A

When the receiving device detects that an error has occurred during the transmission of data. The data is then requested again.

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13
Q

Packet switching

A

A data network technology. A message is broken in to packets and then sent across a network using the most suitable routes between the source and destination

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14
Q

HTTP

A

An insecure protocol used between a browser and web server. Hypertext Transfer Protocol transmits HTML web pages from web server to client

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15
Q

HTTPS

A

Secure version of HTTP, the traffic is encrypted between the browser and the web server for security. Now fairly standard

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16
Q

TCP

A

Transmission Control Protocol - this sets up and maintains a reliable connection between two computers, e.g. client’s browser and web server

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17
Q

IP

A

This protocol describes how to route packets of data around networks. Short for Internet Protocol, it’s used by routers and switches to direct packets

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18
Q

IMAP

A

Alternative email protocol to POP, the client can read emails but they stay on the server, short for Internet Mail Access Protocol

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19
Q

FTP

A

Protocol for transferring files to and from a file server. File Transfer Protocol

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20
Q

SMTP

A

Rules for sending emails from client to server, and then server to server. Simple Mail Transfer Protocol

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21
Q

POP

A

Used by client to download emails from mail server. Post Office Protocol is older and less useful than IMAP

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22
Q

Wi-fi

A

Wireless connection standards are known by this 4-letter acronym, this describes how wireless devices connect

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23
Q

Ethernet

A

The protocols used at the lowest layer of a network, describing the rules for connecting hardware and cables

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24
Q

Protocol

A

A set of agreed rules which allow two devices to communicate. SMTP, HTTPS and TCP are all examples

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25
Q

Bluetooth

A

Wireless PAN technology that transmits signals over short distances between smartphones, computers and other devices e.g. headsets and fitness trackers

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26
Q

Encryption

A

Converting readable data into unreadable characters to prevent unauthorized access. Authorised recipients can reverse the process with the key. HTTPS uses it

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27
Q

IPv4

A

A version of the IP protocol that uses 32-bit (4-byte) addresses such as 104.16.15.221. There are only around 4 billion possible IPv4 addresses and we are running out, so IPv6 is now preferred

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28
Q

IPv6

A

The latest version of the IP protocol, it uses 128 bits (16 bytes) for every address so they will never run out. Addresses are shown as 4 pairs of hex bytes like this: a490::65d8:4282:7f30

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29
Q

Number of bits in an IPv6 address?

A

128

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30
Q

Number of bits in an IPv4 address?

A

32

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31
Q

Approximate number of IPv4 addresses, because IPv4 is limited to 32 bits giving 2^32 possible values?

A

4 billion

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32
Q

Standard

A

Published document that says how hardware or software must behave or interact, e.g. the Wi-Fi rules 802.11, the HTML structure and the cable types Cat 5e and Cat 6.

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33
Q

Layer

A

A level in the protocol stack. Protocols in each of these perform related services, and each must talk to the one above and below.

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34
Q

TCP/IP

A

The 4-layer “protocol stack” that makes the internet work. Includes Ethernet, IP, TCP and HTTP which all have a role to play in delivering a services over the web

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35
Q

Network

A

A collection of computers or devices connected via cables or Wi-Fi to share data, peripherals or an internet connection

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36
Q

Node

A

Any single machine connected to a network

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37
Q

Topology

A

The physical arrangement of connected devices on a network, the shape of a network (mesh, star)

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38
Q

Personal area network

A

Small network for data transmission over short distance. For personal use such as headphones, often uses Bluetooth

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39
Q

Local Area Network

A

Network covering a small geographic area such as a building or site. All hardware is usually owned by the user’s organisation, e.g. school.

40
Q

Wide Area Network

A

Network covering a large geographical area such as a city or country. Often uses 3rd party hardware, cables or satellite connections.

41
Q

Wired

A

A physical network connection using a cable

42
Q

Wireless

A

A network connection that uses radio waves

43
Q

Star

A

All devices are connected to a central switch or hub which directs data and requests in this versatile topology

44
Q

Mesh

A

A network topology where nodes have many connections to other nodes meaning it is fast and reliable but expensive

45
Q

Client-server

A

A network model with a central server where files are stored and clients request services from the server. More secure and reliable than peer-to-peer

46
Q

Peer-to-peer

A

All computers on the network are equal in this model and data may be shared between them. Insecure and unreliable but cheap

47
Q

Peer-to-peer networking model is…

A

Cheap

48
Q

Client-server model of networking is…

A

Secure

49
Q

The geographic area of a LAN is…

A

Small

50
Q

A typical business that will use a LAN in a Star topology with a client-server model is…

A

A school

51
Q

Internet

A

The world’s biggest WAN, it’s made of millions of routers connected to other WANs and LANs

52
Q

Server

A

A powerful computer attached to a network that awaits and responds to requests for data from the clients

53
Q

Client

A

A computer that requests data or services stored on a server. The computer you use in school is a client

54
Q

Request

A

A message sent from a client computer to a server asking for data in a client-server network

55
Q

Characteristics of LAN

A

• low-cost
• connects devices in small geographical area
• faster than WAN

56
Q

Characteristics of WAN

A

• large capacity
• slower than LAN
• connect a large number of computers over a large area

57
Q

Factors that affect the performance of networks

A

•Number of devices connected
•Bandwidth
•Type of network traffic
•Network latency
•The number of transmission errors

58
Q

Why do the number of devices connected affect the performance of a network?

A

• A collision occurs when two devices on a network try to communicate along the same communication channel.
• The more number of devices on a network, the more chance of a collision occurring, and the longer it takes to transmit a message.

59
Q

Why does bandwidth affect the performance of a network?

A

The more bandwidth a data connection has, the more data it can send and receive at one time

60
Q

Why does the type of network traffic affect the network performance?

A

•Different types of network traffic usually have different bandwidth requirements.

61
Q

Why does network latency affect network performance?

A

A network with low latency experiences few delays in transmission, whereas a high latency network experiences many delays. The more delays there are, the longer it takes to transmit data across a network.

62
Q

Why does the number of transmission errors affect network performance?

A

the more chance of a collision occurring, the longer it takes to transmit a message.

63
Q

Twisted copper wire typical bandwidth

A

Up to 10 gigabits (Gb) per second

64
Q

Fibre-optic cable typical bandwidth

A

Up to 100 gigabits (Gb) per second

65
Q

Wi-fi (home networks) typical bandwidth

A

Up to 600 megabits (Mb) per second

66
Q

Business Wi-Fi typical bandwidth

A

Up to 6 gigabits per second

67
Q

Client-server networks

A

This type of network separates computers into one of two classifications - servers and clients.

68
Q

Roles of computers in Peer-to-peer networks

A

In a peer-to-peer (P2P) network, all computers have equal status - no computer has control over the network. There are no servers or clients. Instead, each computer is known as a peer. Peers store their own files, which can be accessed by other peers on the network. Therefore, a peer is both a client and a server.

69
Q

wireless access points (WAP)

A

A WAP is a device that allows different types of wireless network cards connect without cables, to connect to LANs and access resources. A WAP plugs into a hub or switch and is the device that joins the unwired network to the wired network.

70
Q

Routers

A

A router receives and sends data on computer networks

71
Q

Switches

A

A switch enables connected devices to share information and talk to each other.

72
Q

NIC (Network Interface Card)

A

provides a computer with a dedicated, full-time connection to a network

73
Q

Transmission media

A

transmits information from the source/transmitter to the receiver.

74
Q

Domain Name Service (DNS)

A

• A DNS is made up of multiple DNSs
• turns domain names (urls) into IP addresses, which allow browsers to get to websites and other internet resources

75
Q

Hosting

A

Hosting is the storing of files and data on a web server. The web server is referred to as a host.

76
Q

The Cloud

A

a term used to describe a global network of servers, each with a unique function

77
Q

File servers

A

Hold and maintain user files

78
Q

Application severs

A

Allow programs to be run over a netwoek

79
Q

Web servers

A

Hold and share web pages

80
Q

Print servers

A

Manage printing across a network

81
Q

Mail servers

A

Handle emails between users

82
Q

How the Server Handles Requests from Clients

A

The client (usually a browser) opens a connection to the server and sends a request.

The server processes the request, generates a response, and closes the connection if it finds a Connection: Close header.

83
Q

what services does the cloud do

A

servers, storage, databases, networking, software, analytics, and intelligence

84
Q

advantages of cloud

A

•Accessibility anywhere, with any device.
•Ability to get rid of most or all hardware and software.
•Centralized data security.

85
Q

Disadvantages of cloud

A

•Cost concerns
•Vulnerability to attacks
•Security and Privacy

86
Q

Advantages of Star topology

A

•It is very reliable – if one cable or device fails then all the others will still work.
•It is high-performing as no data collisions can occur.
•Less expensive because each device only need one I/O port and wishes to be connected with hub with one link.

87
Q

Disadvantages of star topology

A

•the whole network fails if the switch fails as no node can communicate
•a wired star topology requires plenty of cable - in a large network this can be expensive

88
Q

Advantages of mesh topology

A

•messages can be received more quickly if the route to the intended recipient is short
•messages should always get through as they have many possible routes on which to travel
•multiple connections mean (in theory) that no node should be isolated

89
Q

Disadvantages of mesh topology

A

•full mesh networks can be impractical to set up because of the high number of connections needed
•many connections require a lot of maintenance

90
Q

Benefits of wired connection

A

•faster data transfer
•better security
•less traffic in networks

91
Q

Drawbacks of wired connection

A

•Less mobility for users
•Installation time
•Maintenance

92
Q

Benefits of wireless connection

A

•increased efficiency
•access and availability
•flexibility
•cost savings

93
Q

Drawbacks of wireless connection

A

•Less secure
•Installation problems
•Can be slower than wired

94
Q

MAC address

A

A Media Access Control (MAC) address is assigned to each Network Interface Card (NIC) by the manufacturer

95
Q

advantages of layers in network protocols

A

•helps simplify networking protocols by breaking them into smaller units
•also offers greater flexibility