FC0-U71 cheat sheet — every exam topic on one page

IT Concepts and Terminology

CompTIA Tech+ IT Concepts: Computing Basics, Number Systems, Units and Troubleshooting

• Input brings data in, processing calculates and decides, output presents a result, and storage keeps data for later.
• RAM is volatile and loses unsaved work when power fails; storage such as an SSD is non-volatile.
• Binary place values double from the right (1, 2, 4, 8 … 128); one byte holds 0 to 255.
• Octal uses 0 to 7 (three bits per digit); hexadecimal uses 0 to 9 and A to F (four bits per digit), so a byte is two hex digits.
• Convert numbers in different bases to one base before comparing them; 10 in any base equals the base.
• Storage units (KB, MB, GB, TB, PB) and throughput units (bps to Tbps) each step by about a thousand.
• 8 bits = 1 byte: divide Mbps by 8 for MB/s, and multiply a file size by 8 before dividing by link speed.
• Processor speed is measured in hertz (MHz, GHz), throughput in bits per second, capacity in bytes.
• Troubleshooting order: identify, theorize (question the obvious), test, plan and implement, verify and prevent, document.

Infrastructure

CompTIA Tech+ (FC0-U71): Computing Devices, Internal Components and Storage Types

• An e-reader's E Ink screen gives glare-free reading and weeks of battery; a laptop is the portable device with a keyboard that runs full desktop applications.
• A workstation is a powerful computer for one user's demanding work; a server provides services to many clients over a network.
• VR replaces the user's view with a simulated world; AR overlays digital content on a live view of the real world.
• The motherboard connects every component; BIOS/UEFI firmware runs first, performs POST and follows the boot order you set in its setup screen.
• The CPU runs general instructions, the GPU renders graphics, and RAM is working memory — match the upgrade to the symptom.
• Wired Ethernet is the most stable, lowest-latency link; an expansion card can add, upgrade or replace an onboard function, and a monitor must be plugged into a new GPU's own ports.
• RAM is volatile and loses unsaved work at power-off; ROM, SSDs, HDDs and flash drives are non-volatile.
• HDDs are cheapest per gigabyte, SSDs are faster with no moving parts, and NVMe SSDs over PCIe are the fastest.
• A NAS shares files on the local network without internet or a full server OS; cloud storage survives a site disaster and is reachable from anywhere online.

CompTIA Tech+ (FC0-U71): Peripheral Devices and Input/Output Interfaces

• Plug-and-play loads a generic driver automatically; extra features such as programmable buttons or a multifunction printer's scanner need the manufacturer's driver, which takes administrator rights to install (on a work device, ask IT).
• IP-based peripherals are configured by opening their IP address in a browser; change the default admin password first and reserve a fixed address so the device stays reachable.
• A UPS keeps equipment running on battery through a short power cut; a surge protector and a power strip do not.
• A projector needs a video source and suits dim rooms (its image washes out in bright light); a smart TV is a bright, self-contained screen that receives casts; a streaming device adds apps to a screen through HDMI.
• RJ45 copper Ethernet reaches about 100 meters per run (PoE adds power, not distance); SFP fiber modules cover longer links.
• A crimper attaches RJ45 plugs; a cable tester checks the finished cable's wiring.
• NFC works at centimetres, Bluetooth device to device over metres, proprietary RF through a supplied USB receiver, and Wi-Fi through an access point.
• VGA is analog with no audio, DVI (DVI-D) is digital with no audio, HDMI and DisplayPort carry video and audio; HDMI and DVI-D connect with a simple cable.
• Not every USB-C port carries video; Thunderbolt carries data, multi-display video and power on one USB-C-shaped cable. Lightning is Apple's older 8-pin connector.
• Mirroring copies the whole screen; casting hands the stream to the TV so the sending device stays free.

CompTIA Tech+ (FC0-U71): Virtualization, Cloud, Internet Services, Networking and Wi-Fi

• A hypervisor creates and runs virtual machines; the host OS runs on the physical hardware and the guest OS runs inside a VM.
• Hybrid means some systems stay on premises while others run in the cloud; the deployment model and the service model are separate choices.
• IaaS leaves the operating system to the customer, PaaS runs the customer's own code without servers or OS to manage, and SaaS is a finished app the provider maintains.
• Fiber is the fastest service and commonly symmetrical; cable is shared coax; DSL uses phone lines and slows with distance; cellular works on the move; satellite and fixed wireless reach remote areas.
• A MAC address is set by the manufacturer and used by switches inside a LAN; an IP address is assigned by the network and used by routers to reach other networks.
• HTTPS (443) encrypts web traffic; IMAP syncs mail on every device while POP3 downloads it to one; SMTP sends mail; SFTP (22) encrypts file transfers while FTP does not.
• Client/server centralizes files, security and backups; peer-to-peer is cheap and serverless but hard to manage as it grows.
• A modem converts the provider's signal, a router shares the connection between networks, a switch adds wired ports, an access point adds Wi-Fi, and a firewall filters traffic by rules.
• 802.11ac is 5 GHz only, 6 GHz needs Wi-Fi 6E, and a link runs at the best standard both ends support.
• 2.4 GHz reaches farthest but is slowest and most crowded; attenuation comes from distance and walls, interference from other radio sources such as microwave ovens.

Applications and Software

CompTIA Tech+ (FC0-U71): Operating Systems, File Systems and File Management

• The OS sits between applications and hardware: apps ask the OS, and the OS (through drivers) handles each device, so apps run on any supported hardware.
• OS functions: disk management (partitions, formatting), process management (sharing CPU and memory among running programs), application management (install/update/remove), device management (drivers) and access control (who may do what).
• OS types: mobile for phones and tablets, desktop/workstation for one user, server for many users over a network, embedded for dedicated devices such as printers, routers and car systems.
• NTFS for Windows drives needing permissions and encryption; exFAT for large files on removable drives used across operating systems; FAT32 is the most compatible but caps files at 4 GB; ext4 is Linux; APFS (and the older HFS Plus) is macOS, which Windows cannot use natively.
• The last extension is the file's real type: statement.docx.exe is a program. Windows names cannot contain \ / : * ? " < > |.
• Compression saves space (already-compressed JPEG, MP3 and MP4 barely shrink); encryption keeps data unreadable without a key. Full-disk encryption protects a stolen device; file-level encryption protects files from other users of the same PC.
• Use least privilege: Read for view-only, Modify to save changes, Full control only for people who must manage permissions. Read-only and hidden are attributes, not security.
• A service runs in the background without a window, starts before sign-in and survives sign-out; a startup app starts and ends with the user's session.
• A fallback driver such as Microsoft Basic Display Adapter means the graphics card's own driver is not installed. Disk Cleanup frees space; Disk Management manages partitions.

CompTIA Tech+ (FC0-U71): Productivity Software, Web Browser Features and Common Uses of AI

• Match the tool to the output: documents → word processing, recalculating numbers → spreadsheet, slides → presentation, symbols and connectors → visual diagramming.
• An online workspace gives many people one live copy to edit at once; share stored files by link with the least permission needed (view-only when others should not change them).
• Instant messaging is real-time text, an email client manages one or more mail accounts in one app, and conferencing is live audio and video with screen sharing.
• Remote support controls another computer, including unattended access; collaboration software combines a team's chat, files and tasks.
• Private browsing discards history, cookies and form data on close, but downloads and bookmarks stay and the network can still see your traffic.
• A browser profile is one person's own bookmarks, passwords, cookies, history and settings; each profile syncs to its own signed-in account, while private browsing keeps and syncs nothing.
• Disable extensions to troubleshoot (settings kept); remove them when unwanted (settings deleted); install only from the official store.
• Outdated layout after a site update → clear the cache; one new-window button that does nothing → allow pop-ups for that site; app lists supported browsers → use one.
• The default search engine controls address-bar searches, not the start-up page; zoom and font size enlarge text, themes and contrast change colour.
• Ask-and-it-answers is a chatbot, tell-it-to-do-something is an assistant, new content from a prompt is generative AI, recommendations from past behaviour are predictions.
• Treat AI-generated content and code as a draft: check facts, and test code on copies before running it on real data.

Software Development Concepts

CompTIA Tech+ (FC0-U71): Software Development Concepts — Languages, Data Types and Program Logic

• Compiled: translated to machine code once, before running — fast, no interpreter needed, built for one platform. Interpreted: translated statement by statement every run — no build step, portable, but slower and needs the interpreter.
• Scripting automates tasks (PowerShell, Bash); markup tags document structure (HTML predefined tags, XML author-defined tags); query languages retrieve and change database data (SQL); assembly uses mnemonics such as MOV and ADD tied to one processor family.
• Char = one character; string = text of any length; integer = whole numbers; float = numbers with a fractional part; Boolean = true or false (including the result of a comparison).
• Values typed into a form or read from a file arrive as strings: adding to one without converting it concatenates ("12" + 5 → 125) instead of adding.
• Identifier = the name; variable = a value that can change; constant = a value that cannot; array = many values under one name, indexed from 0 in most languages.
• Functions are reusable named blocks: parameters go in, a return value comes out.
• A class is the template; objects are instances; properties/attributes describe an object; methods are what it does.
• Pseudocode plans in plain text that cannot run; flowcharts plan with shapes (oval start/end, rectangle process, parallelogram input/output, diamond decision); comments live inside code, documentation outside it.
• Sequence runs in order; branching (IF/ELSE IF/ELSE) picks the first true path; loops (FOR/WHILE) repeat — trace each pass to find the output.

Data and Database Fundamentals

CompTIA Tech+ (FC0-U71): Data and Database Fundamentals — Value of Data, Database Structures and Backups

• Data is raw facts; information is data processed into meaning. Data valued and protected like equipment is an asset.
• Critical data stops the business if lost and cannot be re-created — protect and back it up first.
• Data monetization earns revenue from data, directly (selling or licensing) or indirectly (using it internally to sell more).
• Capture records data at its source; analytics finds patterns; correlation shows two things move together but does not prove cause.
• Big Data is too large, fast or varied for traditional tools: volume, velocity, variety, veracity.
• A query finds records; a report presents them. Import brings data in; export sends it out.
• Databases add persistence, concurrent users, scalability and speed; a flat file such as a CSV is simple and portable.
• Structured = fixed columns; semistructured = labeled but flexible (JSON, XML); non-structured = media and free text.
• A primary key uniquely identifies a row; a foreign key points at another table's primary key; constraints enforce the rules.
• Backup type decides what comes back (files vs whole system); location decides what it survives (off-site, disconnected, versioned) — and test restores.

Security

CompTIA Tech+ (FC0-U71): Security Concepts and Device Security

• Seen without permission = confidentiality; changed without permission = integrity; can't reach it = availability.
• Privacy on a platform is set by that platform's sharing settings: privacy settings on social sites, named people instead of 'anyone with the link', BCC for groups of strangers.
• PII is anything that can single out one person; GDPR protects people in the EU wherever the company handling their data is based.
• Cookie consent covers non-essential cookies; strictly necessary cookies, such as a sign-in session, still work after 'Reject all'.
• Authentication = who you are; authorization = what you may do; accounting = what you did; non-repudiation = you can't deny it. Logs record the account, so shared logins make actions untraceable to a person — even with MFA.
• Multifactor means two or more different factor types; two things you know is still single-factor. Single sign-on = sign in once, use many apps.
• Least privilege: everyday work in a standard account, admin rights only when needed and tied to one person so actions stay traceable.
• Social engineering relies on urgency and trust; verify requests through a contact method you already trust.
• Patching fixes device flaws, anti-malware catches malicious files, a firewall filters connections, a VPN protects traffic; a cable lock stops theft, a USB lock stops plugging in.
• Perpetual = keep using that version forever; subscription = pay to keep using. Get software from the OEM/developer or the official app store, and uninstall unwanted extras properly, then scan.

CompTIA Tech+ (FC0-U71): Password Best Practices, Encryption Use Cases and Wi-Fi Security

• Length adds the most password strength; predictable complexity tricks (capital first letter, 0 for o, a year at the end) are what cracking tools try first.
• Complexity = mix of character types; history = blocks earlier passwords; expiration = limits how long a password stays valid; lockout = reacts to failed sign-ins.
• Reusing a password lets a breach of one site unlock every other account that shares it; a password manager stores a unique password per site in an encrypted vault behind one master password.
• Never share a password; verify identity before any password reset; secure reset links go only to the address on file, work once and expire.
• Change default usernames and passwords on every new device, and make sure devices require a password at startup and on wake.
• A valid certificate proves the site's identity and enables HTTPS — not that the site is honest or malware-free; on an invalid-certificate warning, leave without signing in. Clear browser history on shared computers, avoid pirated software, and never paste personal or confidential data into AI tools.
• Encryption turns plain text into ciphertext with a key; data at rest and data in transit each need their own protection.
• Disk-level encryption covers the whole drive against theft but is transparent once signed in; file-level encryption protects chosen files even from other users of the computer.
• HTTPS covers one website's traffic, a VPN covers all traffic to its endpoint, email encryption protects the message itself, and end-to-end app encryption keeps even the provider out.
• For Wi-Fi: change the router admin password and default SSID, use WPA3 (or WPA2/WPA3 mixed for older devices), and never rely on hiding the SSID or MAC filtering.