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  • OCR CTech IT | Unit 1 | 3.3 - Network Characteristics | CSNewbs

    3.3 - Network Characteristics Exam Board: OCR Specification: 2016 - Unit 1 Network Topologies Network topology refers to the . arrangement of computer systems on a network Devices in a network topology diagram are often called . 'nodes' Client-Server Network make to a , the server manages that request and responds. For example, if the user (client) makes a request to access to a web server. Clients requests server www.bbc.co.uk ​ Large services like Amazon and Google will need very powerful servers to handle millions of requests a second. ​ The client is completely to provide and manage the information. The server controls , and to manage higher demand. dependent on the server network security backups can be upgraded Disadvantages: Large amounts of will cause the . traffic congestion network to slow down If a then the . fault occurs with the server whole network will fail may be required to . IT technicians manage and maintain the network , such as viruses, can across the network. Malware spread quickly Peer-to-Peer Network For , . Each computer is equally responsible for providing data. peer-to-peer networks data is shared directly between systems without requiring a central server Peer to peer is that can then be downloaded. optimal for sharing files Bus Topology The nodes are connected to a (a which transfers all data on the network). bus central cable How it works: The bus . transfers data packets along the cable As the data packets arrive at each computer system, the computer checks the contained in the packet to see if it . destination address matches its own address If the address , the computer system passes the . does not match data packet to the next system If the address of the computer system the destination address in the data packet, it is accepted and processed. matches At both ends of the cable are to mark the end of the bus. terminators Advantages: Because of the simple layout, it is to the main cable . easy to attach another system without disrupting the whole network A bus topology is once the main cable has been established making it . quick to set up optimal for temporary networks A bus topology is because it usually contains than other topologies and (like a hub or switch). cost-effective less cabling requires no additional hardware Disadvantages: Poor security as data packets are passed on to each system on the network. Data collisions are likely - this is when two systems attempt to transfer data on the same line at the exact same time. Resending the data wastes time and slows down the network . The main cable will only have a limited length which can become crowded and slows network speed as more systems are attached. The main cable must also be terminated properly . Token Ring Topology In a , computer systems are connected in a ring or a loop. token ring network How it works: A (small data packet) is sent around the ring in one direction, being passed from one computer system to the next. A and includes its own data when it transfers data. As the token arrives at each computer system, the system checks the contained in the packet to see if it matches its own. If the addresses match, the computer processes the data otherwise it ignores it. token computer seizes the token destination address Advantages: as data packets are around the ring. Data collisions are avoided transmitted in one direction to a ring topology as much as other layouts like a bus topology because the data is transferred at a . Attaching more systems won't affect the transfer speed consistent speed Disadvantages: If then the as the loop is broken and data can't be transferred to all systems. any system on the network fails whole network fails To to a ring topology the . add a new system network must be temporarily shut down Star Topology In a , each computer system is connected to a . star network central node: a hub or switch How it works: Each node is connected to the central node (usually a ) and transfers its data packets here. The hub/switch looks at the and transfers the packets to the intended computer only. hub or switch destination address Advantages: A star topology has because data packets are in the centre and not necessarily all devices like in a bus or ring topology. improved security sent directly to and from the hub / switch to the central system so the . System failures of attached computers won't usually cause complete network failure. New systems can be attached directly network doesn't need to be shut down are generally in a star topology as there are . Transfer speeds fast minimal network collisions Disadvantages: (the hub or switch) is to be purchased, installed and maintained. Extra hardware required (the hub or switch) then the until the error is fixed. If the central system fails whole network will be unusable Mesh Topology In a mesh network, . each computer system is connected to every other computer system How it works: Data packets are transferred to the along the quickest path, travelling from node to node. If a pathway is broken, there are many alternative paths that the packets can take. destination address Advantages: If one cable or system fails then and still reach the destination address. data packets can take an alternative route Because of the large possible number of systems and connections, a mesh topology can usually . withstand large amounts of data traffic to the network . New systems can be added without disrupting the entire topology Disadvantages: Because of the possibly required (especially in a complete mesh topology) this network layout can be . large amount of cables expensive to install and maintain should be avoided - this is when cables are that . Redundant cabling connected between systems won't ever need to communicate Configuration Before a computer system can use a network, must be (set up) correctly. three pieces of information configured IP Address An is used to , allowing communication between them. IP address uniquely identify computer systems on a network ​ ​An example of an IP address is 195.10.213.120. Default Gateway When , it . data is to be sent from one network to another must be sent through a default gateway This default gateway is usually a that connects the local network to another network. router Network managers can use which is and . automatic configuration quicker easier to set up ​ A new device can connect to and use a network , such as free WiFi in an airport. automatically Network managers can also set which as until the addresses have been . This from connecting to the network. manual configuration improves security new devices can’t be used configured by a technician stops unauthorised devices Subnet Mask is the act of . This helps to and means that users can externally access parts of a network (e.g. emails from home) without having to open the entire network. Subnetting dividing a physical network into smaller 'sub' networks (known as subnets ) reduce traffic ​ A is used to . The mask is used to in a subnet. subnet mask define these subnets determine the start and end address of each IP address ​ A is as making the first 3 sections full restricts the fourth section to 256 unique values. For example 113.12.14.230 and 113.12.14.157 are in the same subnet but 114.12.14.127 wouldn't be. common subnet mask 255.255.255.0 uesto's uestions Q Q 3.3 - Network Characteristics: ​ Describe how networks and networks function. 1 a. peer-to-peer client-server Give one for both types of network. 1b. use ​ ​ and for all . 2a. Draw label a diagram 6 network topologies Describe and of . 2b. 2 advantages 2 disadvantages each network topology ​ 3 What is an ? Why is it for networks? . IP address necessary Describe what is meant by a . 4. default gateway What is ? 5a. subnetting What is the purpose of a ? 5b. subnet mask State a . How many can be used on a network with this subnet mask? 5c. common subnet mask unique devices Describe why a network manager may use and why they may use . 6. 1 reason automatic configuration 1 reason manual configuration Advantages: The network can be from the server to . controlled centrally easily backup data and update software across the network, such as . Hardware, software and resources can be shared printers, applications and data files The network allows for , meaning more clients can be . improved scalability easily added to the central server Disadvantages: Without a dedicated server there is . Backups must be performed on each individual system. no central device to manage security or backups Computer with to the network, especially if other machines are slow. performance will decrease more devices connected Advantages: This is a than client-server as . simpler network to set up no server is required Clients are . not dependent on a server Perfect for , such as downloading media files. quickly sharing files between systems 3.2 - Virtualisation Topic List 3.4 - Connection Methods

  • HTML Guide 1 - Setup | CSNewbs

    1. Setting up a HTML document HTML Guide Watch on YouTube: This guide assumes that you have Notepad++ already installed. ​ If you are working at home and need to download Notepad++ then click here . Save as .html file Notepad++ assumes you are writing a text file so you must . change the file type ​ Open Notepad++ ​ Click then File Save As... ​ Change from to Save as type: Normal text file (.txt) Hyper Text Markup Language file (.html) ​ Change to File name: Fanpage Website.html ​ These steps are necessary to set up your HTML web page correctly. Open Notepad ++ and save your file as a .html document. Editor vs. Browser View In newer versions of Notepad++ click on View then View Current File in and choose a browser installed on your computer such as Chrome . Some versions of Notepad++ enable you to view the document in a web browser by selecting Run then an option such as Launch in Chrome . It is good practice to have both Notepad++ and a web browser open at the same time so that you can easily check if any changes have been made correctly. ​ Remember to press the save icon ( ) before you refresh your browser . ​ Don't expect your web browser to show anything yet . Next it is time to add our essential tags for the structure of the web page. HTML Guide 2. Essential Tags

  • HTML Guide 3 - Text Tags | CSNewbs

    3. Tags for Text HTML Guide Watch on YouTube: Remember to write the tags for everything you want the user to see between the and tags. Headings Time to add text to your web page such as headings and paragraphs. To write a , use large heading and ​ To write headings in a smaller size, use numbers between 1 and 6. Add a large heading and a sub-heading to your webpage. Paragraphs Typing text between the tags will create a . and paragraph Add at least three different paragraphs to your webpage. Bold, Underline & Italics You can format your text by changing it to be bold , underlined or italicised (slanted). Now you have text on your web page, you can add hyperlinks to take viewers to different websites. In the paragraphs you have already written, add at least 1 bold tag, 1 underline tag and 1 italics tag. 2. Essential Tags HTML Guide 4. Hyperlinks

  • HTML Guide 10 - More Pages | CSNewbs

    10. More Pages HTML Guide Watch on YouTube: Create a New Page Create a new page by either clicking the in Notepad ++ or selecting then . new page icon File New ​ Then you need to your new page with an appropriate name as a . save HTML file Create a new page, save it and add information to it. Your new page needs the same as your original page: essential tags ​ Then you can . add the rest of your content Link to Other Pages The = tag is used to , just like it is used to hyperlink to other websites. link between pages ​ Make sure you as you have saved them. type your web pages exactly ​ Make sure all of your web pages are . saved in the same folder Include links between pages on each new page. A link to the second page. Don't forget a on each new page. link back to your homepage Why not add more pages to make your website more detailed? 9. Colours & Fonts HTML Guide

  • HTML Guide 8 - Videos | CSNewbs

    8. Videos HTML Guide Watch on YouTube: Embedding a video from YouTube into your web page is very easy. YouTube Videos Find an appropriate video on YouTube and click the button underneath the video. Share Next, click the option. Embed Embed a video onto your web page. that is displayed on your screen and it directly into your HTML document. Copy the HTML code paste Next you can customise your web page with a background colour and different font styles. 7. Head Tags HTML Guide 9. Colours & Fonts

  • HTML Guide 6 - Organisation | CSNewbs

    6. Organisation HTML Guide Watch on YouTube: This page explains the following tags which can be used to structure a simple page layout: ​​ Horizontal Line Centre Quote Bullet Points Numbered Points Horizontal Line You can add a horizontal line by simply adding to your document. ​ There is no close tag. Add at least one horizontal line to your web page. Centre Align This tag places the content within the tags on the . centre of the page ​ Be careful - you need to use the American spelling - ' ' - in your tags. center Add tags to place your main heading in the centre of the page. Blockquote A blockquote is used to from another person or place. display a quote ​ Text is further from the margin than the other content. indented ​ It is not used very often, but can be found in some online articles and essays. Add at least one block quote to your web page. Unordered List An unordered list is a set of . bullet points ​ The tag is placed before the bullet points and afterwards. ​ Each bullet point is placed within tags. That stands for . list item Add either an unordered or ordered list to your web page. Include at least three items in your list. Ordered List An ordered list will . number each line ​ The tag is placed before the list and afterwards. ​ Each list item is placed within tags. Add either an unordered or ordered list to your web page. Include at least three items in your list. Next it is time to add tags to the head, including a page title and metadata. 5. Images HTML Guide 7. Head Tags

  • HTML Guide 7 - Head Tags | CSNewbs

    7. Head Tags HTML Guide Watch on YouTube: Remember that all HMTL documents are split into the head and the body. ​ . The following tags must be typed inside of your head tags Title The title is not the main heading. ​ The title is the itself that you can see at the at the top of your web browser. page title tab Add a title to your web page. Metadata Metadata is itself. information about the web page ​ This commonly includes data about the author, the page's contents and any keywords. ​ . Metadata will not appear on the actual web page Add meta data tags between your head tags for author, keywords and a description. The is made up of a and . meta tag name content ​ represents who created the web page. Author are commonly used words. Keywords is used for displaying search engine results (such as a Google search). Description Next it is time to embed YouTube videos into your web page. 6. Organisation Tags HTML Guide 8. Videos

  • HTML Guide 5 - Images | CSNewbs

    5. Images HTML Guide Watch on YouTube: Images can be added to your web page to make it more visual. ​ The guide below shows you how to find a picture online, download it and place it in your web page. Find & Save the Image Firstly you can perform a to find a picture that you like. Google Image search ​ As an ethical Computer Scientist, you should be searching for images. copyright free Click on Tools and then Usage Rights to change it to 'Labeled for reuse'. Choose an appropriate image and download it to the same folder as your html file. . Save the image in the same folder as where your HTML file is saved ​ . If you don't do this, your image won't work If you are using a school computer and the , without giving you the option to rename it and save it, click on 'Show in folder' and . image automatically downloads move it to the folder where your HTML file is Make sure that the image is saved in the exact and that is has a . same folder as your HTML file suitable name Create the Image Tag The tag for images - it is all written within one set of angle brackets. does not have an end tag ​ stands for . src source ​ You must type the image , including the (e.g. .jpg or .png). Don't forget the either. exactly as it is saved file type speech marks Create the img tag, using the exact name of the image you downloaded. Change the Image Size You can directly state the width and height of the image by defining the style within the image tag. If your image is too large or too small, change the size of it yourself. Next it is time to organise the web page further so it looks more like a professional site. 4. Hyperlinks HTML Guide 6. Organisation

  • HTML Guide 9 - Colours & Fonts | CSNewbs

    9. Style (Colours & Fonts) HTML Guide Watch on YouTube: Before you add any colours or font styles, you need to add and tags. ​ The style tags must be written within your head of your HTML document! ​ Add them below your title tags: Add the

  • HTML | CSNewbs

    I'm Arthur the Alligator and I'm here to teach you HTML. HTML GUide Show me how to make a webpage in HTML from scratch. List of Tags Show me a list of tags I can use.

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