Computer Knowledge Questions for SSC CGL

Hardware vs Software

Hardware is the physical machine you can touch—CPU, RAM, motherboard, keyboard, monitor. Software is the instructions and programs that run on hardware—Windows, Chrome, Excel. Think of hardware as the body and software as the brain and instructions. SSC CGL tests your ability to classify components and understand their roles.

• Hardware: tangible, electronic components that process and store data
• Software: intangible programs, operating systems, and applications
• Firmware: software embedded in hardware (BIOS, ROM)
• Common hardware: CPU, RAM, HDD, SSD, GPU, motherboard, PSU
• Common software: OS (Windows, Linux, macOS), applications (MS Office, browsers)
• Peripheral devices: input (keyboard, mouse), output (monitor, printer), storage (USB, external HDD)

CPU and Memory Hierarchy

The CPU is the brain of the computer. Memory hierarchy refers to the speed and size trade-off: faster memory is smaller and more expensive. Registers are fastest but tiny, then L1/L2/L3 cache, then RAM, then storage. SSC CGL asks about CPU functions, clock speed, cores, and why RAM is different from storage.

• CPU (Central Processing Unit): executes instructions, measured in GHz (gigahertz)
• Cores: number of independent processing units; more cores = better multitasking
• RAM (Random Access Memory): fast, temporary, volatile memory—data lost on shutdown
• ROM (Read-Only Memory): permanent, non-volatile, stores firmware
• Cache: ultra-fast memory on CPU; L1 smallest/fastest, L3 largest/slower
• Storage (HDD/SSD): permanent, non-volatile, slower than RAM but holds data after shutdown

Operating Systems and File Management

An operating system manages hardware resources and provides a user interface. SSC CGL tests knowledge of popular OS types, their functions, and basic file system concepts. Windows, Linux, and macOS are the main desktop OS. Mobile OS include Android and iOS. File systems organize data in directories and folders.

• OS functions: manage hardware, run applications, provide user interface, handle security
• Windows: most common desktop OS, user-friendly, proprietary
• Linux: open-source, free, used in servers and embedded systems
• macOS: Apple's OS, premium, Unix-based
• Android: Google's mobile OS, open-source, most used globally
• File system: hierarchical structure of folders and files; common types: NTFS, FAT32, ext4

Networking and Internet Basics

Networking connects computers to share data and resources. The Internet is a global network of networks. SSC CGL tests understanding of IP addresses, protocols, bandwidth, and basic networking devices. Know the difference between LAN, WAN, and the Internet.

• IP Address: unique identifier for devices on a network; IPv4 (32-bit) and IPv6 (128-bit)
• LAN (Local Area Network): computers in a small area (office, home)
• WAN (Wide Area Network): computers spread across large distances
• Router: connects networks and directs data packets
• Modem: converts ISP signal to usable internet connection
• Bandwidth: amount of data transmitted per unit time, measured in Mbps or Gbps
• HTTP/HTTPS: protocols for web communication; HTTPS is secure (encrypted)
• DNS: translates domain names (google.com) to IP addresses

Cybersecurity and Data Protection

Cybersecurity protects computers and networks from unauthorized access and attacks. SSC CGL asks about common threats, passwords, encryption, and safe practices. Understand malware types, phishing, and why backups matter.

• Malware: malicious software including viruses, worms, trojans, ransomware, spyware
• Virus: replicates by attaching to files; requires user action to spread
• Worm: self-replicating, spreads without user action
• Trojan: disguises as legitimate software, opens backdoors for attackers
• Phishing: fraudulent emails/messages to steal credentials or data
• Encryption: converts data into unreadable code; only authorized users can decrypt
• Firewall: blocks unauthorized network traffic
• Antivirus: detects and removes malware
• Password best practices: strong (mix of letters, numbers, symbols), unique, changed regularly
• Backup: copy of data stored separately to recover from loss or corruption

Input/Output Devices and Peripherals

Input devices send data to the computer; output devices receive data from the computer. SSC CGL tests classification and basic function of common peripherals. Know the difference between input and output, and recognize newer devices.

• Input devices: keyboard, mouse, touchpad, scanner, microphone, camera, joystick
• Output devices: monitor, printer, speaker, headphones, projector
• Input-Output devices: touchscreen, printer-scanner combo (multifunction)
• Storage peripherals: USB flash drive, external HDD, SD card, optical drive (CD/DVD)
• Monitor types: LCD, LED, OLED; measured in inches and resolution (1080p, 4K)
• Printer types: inkjet (color, home use), laser (fast, office), thermal (receipts)

Software Types and Applications

Software is categorized by purpose and licensing. System software manages hardware; application software performs user tasks. SSC CGL tests understanding of software categories, licensing models, and common tools.

• System software: OS, drivers, firmware—manages hardware and system resources
• Application software: productivity (MS Office), media (VLC), browsers (Chrome), games
• Freeware: free to use, proprietary, no source code access
• Open-source: free, source code available, can be modified
• Paid/Commercial: licensed, often with support and updates
• Cloud software: runs on servers, accessed via browser (Google Docs, Office 365)

Data and File Formats

Files are stored in specific formats depending on content type. SSC CGL tests recognition of file extensions and their purposes. Know common formats for documents, images, audio, and video.

• Document formats: .doc/.docx (Word), .pdf (portable), .txt (plain text), .xlsx (Excel)
• Image formats: .jpg (compressed, photos), .png (transparent), .gif (animated), .bmp (uncompressed)
• Audio formats: .mp3 (compressed), .wav (uncompressed), .flac (lossless)
• Video formats: .mp4 (common), .avi (older), .mkv (high quality), .mov (Apple)
• Compressed formats: .zip, .rar, .7z—reduce file size for storage and transfer

• Confusing RAM with storage: RAM is temporary and fast; storage is permanent and slower. Data in RAM is lost when powered off.
• Thinking all viruses need user action: Worms self-replicate and spread without user interaction; viruses typically require opening an infected file.
• Mixing up input and output: Input devices send data TO the computer (keyboard, mouse); output devices receive data FROM the computer (monitor, printer).
• Assuming HTTPS is completely unhackable: HTTPS encrypts data in transit but doesn't protect against phishing or weak passwords.
• Not knowing the difference between LAN and Internet: LAN is local (office network); Internet is global. Your home WiFi is a LAN; the web is the Internet.
• Forgetting that Linux is free and open-source: Many aspirants think all OS are paid; Linux is free and widely used in servers and embedded systems.

• HAS RAM: Hardware, Applications, Storage = RAM (temporary memory). Remember RAM is fast but temporary.
• VIRUS vs WORM: Virus needs a host (like a biological virus); Worm is independent (like a worm in soil).
• INPUT = IN, OUTPUT = OUT: Input goes IN to computer (keyboard, mouse); Output goes OUT from computer (monitor, speaker).
• LAN = Local, WAN = Wide: LAN is your office/home network; WAN spans cities/countries.
• HTTPS = HTTP + Security: HTTPS is the secure version of HTTP; the S stands for Secure (encrypted).
• MALWARE MENU: Virus, Worm, Trojan, Ransomware, Spyware—remember as VWTRs (or just recall each separately).

• SSC CGL Reasoning includes 5-8 computer knowledge questions, typically in the second half of the section. These are usually direct definition/classification questions—high-scoring if you know terminology.
• Recent papers focus on cybersecurity (malware types, phishing, encryption) and basic networking (IP, DNS, LAN/WAN). Spend extra time on these areas.
• Questions often ask 'Which of the following is an input device?' or 'What is the function of a firewall?'—straightforward recall. Memorize definitions and categories.
• File format questions appear occasionally: 'Which format is used for compressed files?' or 'What does .pdf stand for?'—know common extensions and their purposes.
• Operating system questions test knowledge of Windows, Linux, and macOS—their characteristics and use cases. Linux's open-source nature is a favorite topic.
• Time management: These questions take 30-45 seconds each if you know the answer. Don't overthink; if unsure, move on and return later.