UNIT 1 EXAM REVISION

UNIT 1 EXAM REVISION

1. 1.6 System Security

   • Malware-(Malicious Software) Malware is software that has been designed for harmful purposes
     • Virus- Software that copies and replicates itself from system to system whilst damaging them
     • Trojan Horse- Malware that is designed to disguise itself as a harmless website or download then causes damages once downloaded onto the system
     • Spyware-A form of malware that monitors a system and records passwords and other sensitive information
     • Ransomware-Another form of malware that locks the user out of all systems until a large amount of money is paid to the programmer
   • Types of System/Network attacks
     • SQL Injection-A malicious code that changes the SQL server statement in an attempt to get unauthorized access to data
     • Phishing- Phishing involves using emails to appear to be innocent links but containing ln that will attempt to steal personal information
     • Brute Force Attack-Brute Force attacks involve trying every possible password combination in an attempt to access accounts
     • Denial of service (DOS) Attack- A DOS Attack involves flooding a server/network with requests to drastically slow the speed or shut it down all together, a DDOS attack (Distributed Denial Of Service) is a variant that involves multiple computers
     • Data Interception/Theft- Data interception and theft involves using packet sniffing and hijacking software to redirect the packets sent out by a network to steal sensitive information such details or passwords
   • Social Engineering- Includes a number of techniques that are used to trick people into giving away passwords such as phishing and impersonation
   • Poor Network Policies- Poor Network Policies are usually the cause of security issues on LAN based or even WAN based systems as workers/users can easily access sensitive or classified data despite what their role or authorizations is
   • Methods of data and network protection
     • Penetration Testing- Purposefully hiring someone with hacking experience or knowledge to attempt to hack a network to find security loopholes
     • Network Forensics-The process of analysing network traffic to attempt to see suspicious actions
     • Network Policies- Sets of rules for a network that users have to agree to
     • Anti-Malware Software- Protection software that constantly scans a computer system and quarantines then deletes any suspicious files
     • Firewalls- Pieces of software or hardware that monitor and if necessary intercept network traffic that appears suspicious
     • User Access Levels-Levels of security that determine if a system user should be able to access certain data
     • Passwords- The stronger a password the harder it is for people to breach the system or use brute force attacks
     • Encryption- The process of scrambling data before it is sent across a network. Only the person with the encryption key can decipher it

2. 1.3 Secondary Storage

   • Types of storage
     • Magnetic Storage- A type of storage that uses lasers and a magnet to create a magnetised segment. E.g. HDD's (Hard Disk Drives) and floppy disks
     • Optical Storage- A storage type that laser burns marks onto reflective disks. E.g. CD-ROM, DVD-ROM and Blu-Ray ROM
     • Flash Storage- A storage type that uses electricity to open and close gates on a circuit board. E.g. USB sticks, SD cards and SSD's (Solid State Drives)
   • Key Terms
     • Capacity-How much data the storage type/device is capable of storing
     • Access Speed-The speed at which the storage device reads/writes data
     • Portability-The level to which a storage device can be carried
     • Durability- How hard it is to damage a storage device
     • Reliability-How long a storage device lasts until it breaks
     • DNS (Domain Name System)-The system that converts a web page URL into its IP address
     • Hosting-The process of storing a web page so it can be accessed on the internet
     • The cloud-Storage that can be accessed through the internet

3. 1.1 System Architecture

   • CPU (Central Processing Unit)
     • The CPU is the component of a system that completes the processing and "fetches and executes" instructions from the main memory
     • Factors that affect CPU performance
       • Clock speed-This is the number of times the CPU "fetches and executes" per second and is measured in Hz (Hertz). 2GHz is the equivalent of 2,000,000,000 cycles per second
       • Number of cores-Modern CPUs have more than one core installed. This is because the more cores that there are, the more instructions can be processed at one time. For example, a dual core processor that process 2 instructions at once
       • Cache- The cache is located directly on the CPU and stores all the commonly used instructions. This allows the CPU to run commonly used instructions quicker. The larger the cache the more commonly used instructions that can be accessed which increases the CPU perform faster
   • Embedded Systems
     • Embedded systems are systems that are completely integrated within the devices they are designated to control
     • Embedded systems still posses all components of standard computers e.g. CPUs and fetch-execute cycles
     • Examples
       • Washing Machine
       • Plane
       • Microwave
   • Von Neumann Architecture
     • Modern CPUs are still based off of the design created by John Von Neumann. They use a series of small storage locations on the CPU known as registers which are used in the fetch-execute cycle.
     • PC (Program Counter)- The PC points to the next instruction in memory and copies its memory address value to the MAR (See MAR). The PC has 1 added to it so that it points to the next instruction
     • MAR (Memory Address Register)- The MAR receives memory addresses from the PC and sends them along the address bus to the correct location within the memory
     • MDR (Memory Data Register)- The instructions and data sent along the data bus is stored within the MDR
     • Accumulator- The accumulator stores the results of executed instructions and holds a running total of the operations currently happening

4. 1.7 Systems Software

   • Software that provides interface between hardware and software and is used to control hardware
   • User Interface- The part of the OS (Operating System) that the user can see. The user interface allows a user to enter commands and allows the OS to display the results
     • CLI (Command Line Interface)- Commands are entered via typing. A CLI is very fast and powerful but is only suitable for an expert user
     • GUI (Graphical User Interface)- Commands are entered with a mouse or touchscreen and icons that are clicked on. They are slower and not as powerful as the CLI but are suitable for any type of user
   • Types of Management
     • Memory Management- Allows memory to be shared so that more than one process can be stored in RAM at one time. This means that modern operating systems are usually capable of multi-tasking e.g. they let you run multiple programs at once. Memory management also controls virtual memory
     • Peripheral Management- A peripheral is a external device that is plugged into a computer such as a mouse,keyboard,scanner or camera. The OS uses device drivers to act as a link between the hardware and software
     • User Management- Allows you to have different log ins for different users. Also allows you to have user access levels
     • File Management- Allows you to organize files into folders. Also allows you to compress files and make them smaller
   • Utility Software- Software that fixes problems on computers or maintains efficiency of computers
     • Encryption- Encryption scrambles sensitive data so that no one apart from the person(s) who has the encryption key can access it
     • Defragmentation- Defragmentation is used to put data that has been randomly added to a disk back into order
     • Data Compression- Data Compression is used to make files smaller to save space and allow data to be transferred faster. The two types are Lossy and Lossless
     • Backup- A backup copies all important files on a system and stores them elsewhere should the originals be corrupted or destroyed. the two types are a full backup that stores all necessary data and an incremental backup that only stores data that has changed since the last backup

5. 1.5 Network Topologies,Protocols and layers

   • Network Types
     • Star Network- A star network is a network in which all computers are directly connected to a server or switch. The advantages of a star network are that computers can be managed and added easily and if one computer breaks down the others can still work. The disadvantages are that if the server malfunctions/breaks then no computer will work and star networks require specialist equipment
     • Mesh Network-In a mesh network all computers are linked to each other which gives them the same level of importance. The advantages are that they are very robust and reliable and do not have to rely on a server which means that all computers can function if one breaks down. The disadvantage is that the large amount of cabling required for one costs a lot of money
     • Types of protocols
       • TCP/IP-(Transmission Control Protocol/ Internet Protocol) Used for sending data across the internet
       • HTTP-(Hyper Text Transfer Protocol) Used for sending and receiving data about web pages
       • HTTP/S-(Hyper Text Transfer Protocol Secure) Sam purpose as HTTP but data is encrypted
       • FTP-(File Transfer Protocol) Used for sending files
       • POP-(Post Office Protocol Used for receiving emails
       • IMAP-(Instant Message Access Protocol) Used for receiving emails AND syncing them to a server
       • SMTP-(Simple Mail Transfer Protocol)-For sending emails
   • Frequency- The number of oscillations per second a radio wave uses. A Wi-Fi signal operates at frequencies that are split up into channels
   • Wi-Fi Encryption
     • WEP-A WEP uses a form of encryption key which, since its creation, has been found to be vulnerable to brute-force attacks. Hackers could guess a WEP password in minutes
     • WPA- WPA was introduced to cover the vulnerabilities every of WEP. It covers these vulnerabilities by changing the encryption key for every data packet
     • WPA2- WPA2 is an even stronger version of WPA that uses 128 bit encryption
     • WPA3- Released in January of 2018, WPA3 uses 192 bit encryption and even features extra security to protect those with weak passwords
   • Ethernet- A protocol that governs data transmission between devices. It transmits data through a LAN using cables. Ethernet uses broadcast addressing which means that if a device sends out some data then all devices on the attached network receive it.
   • IP vs MAC Address- An IP Address is something given to anything connected to the internet and is a unique number that identifies a computer/device. A MAC address is a unique number wired into all pieces of network equipment and never changes

6. 1.8 Ethical, Legal, Cultural and Environmental

   • Environmental Effects
     • Good
       • Using Computers saves paper and reduces the amounts of paper we store or waste
       • Video Conferences reduces the need for travelling, lowering pollution
       • People are able to work from home which also reduces pollution as well as traffic
     • Bad
       • Computers use energy which means fossil fuels are burned
       • Computers are full of hard-to-dispose of chemicals that can damage the environment if they end up in landfills
   • Cultural Implications
     • internet Access
       • Some countries have physical barriers such as mountains to technology
       • Some countries heavily filter the internet
       • Many countries don't have the infrastructure to support the internet
     • Access to IT education
       • Many countries can't afford the level of Western education
       • Some countries ban certain citizen types (e.g. Saudi Arabian Women) from education
       • Older citizens are excluded from the technological world
     • Legal implications
       • The Data Protection Act 1998- The law that prevents the misuse of personal information
       • The Computer Misuse Act 1990- The law that prevents people from using computers for illegal/harmful reasons
       • The Freedom Of Information Act 2000- The law that allows the public have access to any information held by the government
       • The Copyright And Patents Act 1998-The law that protects published works and makes sure only creators get rewards from those works
       • Creative Commons Licensing- A type of license that allows an author to give their work away

7. 1.2 Memory

   • RAM (Random Access Memory
     • RAM stores instructions and data from programs that are currently in use
     • RAM is a volatile memory type which means when the power to the system is shut off all contents are lost
     • The two types of RAM are DRAM (Dynamic RAM) which is cheap but slow and requires constant refreshing and is also used as the main RAM within your computer and SRAM (Static RAM) which is expensive yet much faster than DRAM and doesn't require lots of refreshing. SRAM is used for cache
   • ROM (Read Only Memory
     • ROM stores the computers' boot up procedures and instructions
     • ROM is non-volatile and keeps its contents when it loses power
     • Some types of ROM such as PROM,EPROM and EEPROM allow the user to write data as well as read it
   • Virtual Memory- Virtual memory acts as an overflow when the RAM reaches capacity. The data that goes into virtual memory must first be processed and converted into RAM which makes virtual memory much slower than RAM
   • Cache Memory
     • Cache memory is what the CPU uses to combat slow speed in the fetch-execute cycle. Cache memory is extremely fast and located near the CPU which allows quick access. Cache stores commonly used instructions and due to its close proximity to the CPU it can greatly affect the CPU performance
   • Flash Memory- Flash Memory is a completely re-writable form of ROM and is much quicker than HDDs (Hard Disk Drives). Flash is commonly used in secondary storage devices such as flash drives or SD cards
   • Innovations in memory
     • The creation of flash memory has led to large developments in system memory such as ultra fast SSDs (Solid State Drives) and larger storage in mobile phones
     • Some possibilities of memory in the future include memory bits the size of just 12 ATOMS, non-volatile RAM and even memory so fast the speed can not be measured

8. 1.4 Wired and Wireless Networks

   • A network is two or more computers that are connected together. This allows: Files to be shared and resources to be shared.
   • Types of networks
     • LAN (Local Area Network)- A LAN is a wired network which means it is connected to computers via wires. The advantages are that it is quick and cheap to set up, cheap to maintain and usually fast. However the disadvantages are that it can only cover a small area and be connected to few computers
     • WAN (Wide Area Network)- A WAN is a network that connects to computers wirelessly. The advantages of a WAN are that it can cover very large areas, even the world and allows multiple computers to be connected. The disadvantages are how it is expensive to set up, requires near constant maintenance, needs specialised equipment and runs quite slow
   • Types of network hardware
     • Wireless Access Point- Allows a device to connect to a LAN via Wifi
     • Router- Connects networks together, normally a LAN to the internet.
     • Switch- Decides where data travels within a network so a device can get the data it requires
     • NIC (Network Interface Card)- Allows a computer to have a wired connection
     • Transmission Media- Transmission media refers to the cabling used to connect networks together. E.g. Ethernet cables, coaxial cables and fibre ooptic cables
   • Factors that affect network performance
     • Wireless networks
       • Distance from wireless access point
       • Physical objects e.g. walls or floors
       • Other devices causing interference
     • Wired Networks
       • Ethernet signal degradtion
       • Cable type used
     • All network types
       • Network traffic (The amount of users on a network)
       • Bandwidth (The amount of data that can be transferred in a second)
       • Latency (How long it takes data to travel through a network)
   • Client Server vs Peer to peer
     • Client Server- A client server has one central computer that processes and stores most of the data. The advantages of a client server are that files are easy to manage as they are stored centrally, backups and security are also controlled centrally making them more secure and you can have access levels. However, the disadvantages are that it needs a specialist operating system, you usually need a network manager and you need specialist equipment
     • Peer to peer-In a peer to peer server all computers have the same role/ amount of importance. The advantages are that there is no need for an operating system, it is easy to set up and the network can still work if one computer fails. The disadvantages are that files are harder to find as they are stored individually, all users must be trusted and there are no user access levels

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