Chapter 5: Networking Flashcards Preview

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Flashcards in Chapter 5: Networking Deck (71):
1

Network

A collection of computers and peripheral devices connected together

2

What are a few types of networks?

1. LANs
2. WANs
3. MANs

3

LAN

Local Area Network: a collection of computers and peripherals connected together within a limited area

4

What kind of areas are LANs used in?

1. Residences
2. Schools
3. Laboratories
4. Office buildings

5

WAN

Wide Area Network: a collection of computers and LANs connected together over a large geographical area, often using leased infrastructure

6

MAN

Metropolitan Area Network: spans an entire city or campus, formed by connecting together multiple LANs

7

Order the following network types in ascending order of size:
1. MANs
2. WANs
3. LANs

3 1 2

8

What three main categories does the use of networks benefit?

1. Sharing resources
2. Communication
3. Centralised management

9

Advantages of using networks for Sharing Resources (3)

1. Shared resources can be accessed anywhere on the network from any computer
2. Ability to use shared peripheral devices, e.g. printers and scanners
3. Internet connection can be shared

10

Advantages of using networks for Communication (3)

1. Email can be used to communicate with colleagues
2. Messaging systems can be used to chat while working
3. Files can be transferred between computers easily

11

Advantages of using networks for Centralised Management (4)

1. User profiles and security can all be managed centrally
2. Software can be distributed across the network as opposed to individual installation
3. Users can use any PC on the network and access their own files
4. Data can be backed up centrally

12

Disadvantages of using networks (5)

1. Purchasing network cabling and file servers can be costly
2. Managing a large network is complicated and requires training. A network manager usually needs to be employed
3. If the file server goes down, files on the server become inaccessible. The computers can still be used, but are isolated
4. Viruses can spread to other computers throughout a computer network
5. Risk of being hacked, especially with WANs. Security measures, e.g. a firewall, are needed to prevent this

13

Network topology

A schematic description of the layout of a network

14

Bus Network

A topology where each device is connected to the main cable, referred to as the bus. Any device can transmit at any time, but only one transmission can occur along the main bus at any one time

15

Pros and Cons of Bus Networks (3 | 4)

Pros
1. Easy and inexpensive to install
2. Easy to add new computers to network
3. Broadcasting onto a bus is faster than transmitting around a ring network through many devices

Cons
1. Main cable failure leads to the whole network going down
2. Cable failures hard to isolate: affects all attached computers
3. Not secure - all data broadcasted on one cable
4. Performance slows down as the amount of traffic increases

16

Ring Network

A topology where each device is connected to the next in a loop. Uses a token-passing protocol to manage transmission one device at a time

17

Pros and Cons of Ring Networks (3 | 3)

Pros
1. Not dependent on a central computer
2. Token passing protocol is simple and reliable
3. Consistent performance even when there is a lot of traffic

Cons
1. A single node or link failure could potentially disrupt the whole network
2. Not secure - all connections shared
3. Slow - data goes around the whole network

18

Star Network

A topology where each device has its own cable connecting it to a central device, which can be a switch or server

19

Pros and Cons of Star Networks (4 | 2)

Pros
1. Failure of a cable only affects one station
2. Consistent performance even when the network is heavily used
3. Easy to add new computers
4. Most secure - messages transmitted down unshared links

Cons
1. Can be costly to install - lots of cabling needed
2. Dependence on a single switch: if this fails, the whole network goes down

20

What kind of networks are the following topologies used in:
1. Ring?
2. Bus?
3. Star?

1. LANs and MANs
2. LANs only
3. LANs and WANs

21

What two ways can the computers in networks be configured to behave in?

1. Client-server
2. Peer-to-peer

22

Peer-to-peer

A method of organising devices in a network where all devices are of equal status instead of being designated specialised roles. Every computer can access resources on another computer, provided access rights have been granted

23

How are the computers in a peer-to-peer network connected together?

They are cabled together to form a LAN

24

Why might a small company use a peer-to-peer network?

It is not cost-effective to have a specialised server

25

Peer-to-peer:
1. Computer status
2(+/-). Setting up and maintenance
3(+/-). Management
4(+/-). Backing up
5(+/-). Dependency
6. Usage
7(+/-). Number of computers

1. All computers have equal status
2+. Easy to set up and maintain
3-. No centralised management - less secure
4-. Each computer backed up separately
5+. No dependency on a server
6. LANs only
7-. Impractical for over 10 computers

26

Client-server

A method of organising devices in a network where some computers have roles as servers. These provide resources and services to other computers, known as clients. Management of the network and shared resources and files is centralised at the server

27

What are the two kinds of computers used in a client-server network?

1. Servers: holds data and controls access
2. Clients: where the user actually works

28

What is the job of a server computer? (3)

1. To control access to shared resources e.g. files, printers
2. Where all the data is stored, making data storage centralised
3. May have specialised roles e.g. print servers, dedicated to controlling access to shared printers and queuing print jobs

29

How do client and server computers interact with each other in school systems? (4)

1. User logs onto client computer using login details
2. Client computer connects to the server
3. Server verifies user login
4. Server gives user access to files they have permission for

30

How can a client-server network approach be used across a WAN? (2)

1. The browser acts as a client to the web server, which is somewhere in the world
2. Companies have centralised databases, which are accessed across a WAN by applications on client computers

31

Why is the client-server architecture used across a WAN?

It means that the data can be stored in one place, and can still be accessed by a large number of client devices worldwide

32

Client-server:
1. Computer status
2(+/-). Setting up and maintenance
3(+/-). Management
4(+/-). Backing up
5(+/-). Dependency
6. Usage
7(+/-). Number of computers

1. Specialised roles of either clients and servers
2-. Needs a network manager to run the network or web server
3+. Centralised security and management
4+. Backup done from central server
5-. Dependent on central server
6. Large LANs and WANs
7+. Can contain hundreds of computers

33

What is the basic principle of a client-server system? (3)

1. The client requests data
2. The server processes the request
3. The server returns a response accordingly

34

Fill in the blanks:
In client-server architectures, there are __ distinct parts to the coded solution, with a __________ between them. Part of this solution will execute at the __________, part at the __________.

1. 2
2. Network connection
3. Server end
4. Client end

35

Internet

A global computer network providing a variety of information and communication facilities through the use of standardized communication protocols

36

What kind of network is the Internet?

A WAN

37

World Wide Web

An information-sharing model that is built on top of the Internet, making up a subset of the Internet

38

What are some examples of things that are part of the Internet, but not part of the World Wide Web? (4)

1. Email (relies on a mail transfer protocol)
2. Instant messaging OR Internet Relay Chat (IRC)
3. Internet gaming
4. File Transfer Protocol (FTP)

39

Protocol

A set of rules that defines how information is transferred over the Internet

40

HTTP

HyperText Transfer Protocol: the set of rules for transferring files on the World Wide Web

41

What happens when a browser requests a webpage using HTTP? (3)

1. Browser requests webpage
2. Server finds page
3. Webpage is sent back to the browser

42

Standalone applications:
1. Data storage
2. Network connection
3. Number of users
4. Availability needed
5. Code structure
6. Security measures

1. All data stored locally (disk or main memory)
2. No network connection to manage
3. Single
4. Used as needed, can be closed between uses
5. Modular structure less important
6. Local access rights on host PC is sufficient security

43

What happens when a browser sends a request for product information using a form on a webpage, which is connected to a database? (3)

1. Browser sends SQL data request
2. Server selects data from database from database and completes page
3. The webpage with the relevant data filled in is returned to the browser

44

Client-server applications:
1. Data storage
2. Network connection
3. Number of users
4. Availability needed
5. Code structure
6. Security measures

1. Data must be passed between the client and server
2. Must manage a network link
3. Multiple clients per server, so a request queue must be managed
4. Must be available all the time
5. Must be designed and created in a modular fashion
6. Clients have to be authenticated before data sent to them

45

Handshake

The communication between a client and server device that initiates communication

46

Three-way handshake

The TCP/IP handshaking process that consists of three exchanges

47

What are the steps of the three-way handshake? (3)

What is the result?

1. The client sends a SYN to the server
2. The server sends back the client's SYN with an ACK
3. The client sends back an ACK

The client can now communicate with the server.

48

What is:
1. A SYN?
2. An ACK?

1. A synchronisation request
2. An acknowledgement

49

TCP/IP

Transmission Control Protocol/Internet Protocol: the basic communication language of the Internet

50

Static webpage

The contents of the page are all coded into the page itself i.e. it does not have any content that updates automatically

51

Dynamic webpage

A webpage that is populated from a database, meaning that its contents are always current

52

Server end programming

Code that is executed at the server side of a client-server system

53

Client end programming

Code that is executed by the browser at the client side of a client-server system

54

What happens when an Internet sales company makes a website? (3)

1. A basic page layout is made
2. This is populated with relevant product details
3. Contents are usually based on search criteria

55

What are some examples of client-side programming? (4)

1. Storing data in cookies
2. Validating data form entries
3. Flash animations and Java applets that run on a page
4. Displaying pop-up ads when the mouse hovers over keywords

56

Validation

Where the computer software checks that data entered by the user is sensible and conforms to any defined rules

57

Examples of validation checks carried out on the client end (5)

1. Range
2. Type
3. Length: e.g. password length longer than 8 characters
4. Presence: makes sure needed information is entered
5. Format: e.g. postcode, email address

58

What does validation do?

It checks that entered data is reasonable, not whether or not it is correct

59

What does verification do?

It double-checks that data is entered correctly e.g. passwords, email addresses

60

Cookies

Stored on the client computer, used by websites to store data which makes the pages more user-friendly

61

What is an example of what cookies do to make a page more user-friendly?

Prompting the user when they enter a username or search for something on the website

62

Applets

Small client-end programs that are embedded in webpages

63

What are some examples of server-side programming? (5)

1. Retrieving data from a database
2. Populating a page with the latest details
3. Checking usernames and passwords
4. Some forms of validation e.g. existence checks
5. Counting the number of site visitors

64

HTML

Hypertext Markup Language: defines the content and structure of a webpage using tags

65

CSS

Cascading Style Sheets: defines how components within a page will be styled using selectors

66

When creating a website, what is it considered good practice to do?

Use HTML for content and CSS for styling, as opposed to using inline styles

67

How was the content of webpages arranged in the past? (2)

1. The content and style were mixed together
2. In order to get a semblance of webpage design, content such as images were placed in invisible tables

68

Markup language

A language designed for the processing, definition and presentation of text

69

Scripting language

A language that allows you to record a set of repeatable instructions

70

What are a couple of examples of web scripting languages?

1. PHP
2. ASP

71

How can Python be used in web scripting?

Through the use of a special library such as Django