CompTIA A+ Core 1 (220-1201) flashcards

Lithium-ion batteries adhered with adhesive require careful, gentle prying using plastic tools to avoid puncturing the cell and causing fire or chemical hazards.

• Use plastic spudgers, never metal tools
• Punctured lithium cells can ignite or swell rapidly
• Adhesive removal solvents/heat can help loosen safely

Memory trick: Pry gently — a punctured battery can turn into a pocket fire.

A cloud model providing virtualized compute, storage, and networking resources, while the customer manages the OS, middleware, and applications.

• Examples: AWS EC2, Microsoft Azure VMs, Google Compute Engine
• Customer responsible for OS patching and app deployment
• Provider responsible for physical hardware and hypervisor

Memory trick: IaaS = 'I manage the OS and above, you handle the hardware.'

When some devices can access a network printer and others cannot, despite basic network connectivity, local firewall rules or incorrect printer configuration on the affected devices are common culprits.

• Ping success indicates basic network connectivity
• Partial access points to local client-side issues
• Firewalls often block specific service ports

Memory trick: Firewalls Fight to Isolate Resources.

The router IP address a host uses to send traffic to destinations outside its own subnet.

• Required for any communication beyond the local network
• Usually the router's LAN interface IP
• Missing gateway = local access works, internet access fails

Memory trick: No gateway, no gate out of town.

An 8-position, 8-contact (8P8C) modular connector used to terminate twisted-pair Ethernet cabling.

• Used for Cat5e/6/6a Ethernet cabling
• Larger than RJ11 phone connectors
• Terminated using a crimping tool onto the cable's 8 conductors

Memory trick: RJ45 = 4+5=9... no, remember '8 wires, 8 pins, 45 for Ethernet fun'.

IPv6 subnets are created by extending the prefix length; the number of subnets created equals 2 raised to the number of borrowed bits.

• 2^n subnets are created when borrowing n bits
• /64 is the standard IPv6 subnet size, borrowing bits extends it
• Formula: prefix length = original prefix + borrowed bits

Memory trick: '2 to the borrowed bits' unlocks the subnet count — 4 bits opens 16 doors.

802.11ax operates on both 2.4GHz and 5GHz bands but is optimized to leverage 5GHz's wider channel availability and reduced congestion for higher throughput.

• 5GHz has more non-overlapping channels than 2.4GHz
• 2.4GHz has longer range but more interference
• Wi-Fi 6E extends into 6GHz band for even less congestion

Memory trick: 5 is for fewer neighbors — less crowded, more speed.

Plenum-rated cable has a special jacket (often FEP) that emits less smoke and toxic fumes when burned, required by fire code for installation in air handling spaces like drop ceilings and raised floors.

• Required in plenum spaces per fire code
• More expensive than standard PVC cable
• PVC (riser-rated) cable is used in non-plenum vertical spaces

Memory trick: Plenum = 'please, no toxic fumes' in the air ducts.

Indicators that a CPU is operating at temperatures beyond its safe limits, leading to performance degradation or system instability.

• Common symptoms include system freezes, blue screens (BSODs), unexpected shutdowns, and performance throttling.
• Often exacerbated by heavy CPU load.
• Can be caused by inadequate cooling (fan failure, poor thermal paste, dusty heatsink).

Memory trick: Hot Hardware Hinders Happy Operation.

A display technology (Twisted Nematic) known for very fast response times and high refresh rates, but narrower viewing angles and weaker color reproduction.

• Fastest response time of common panel types
• Preferred for competitive/gaming laptops
• Weaker color accuracy and viewing angles than IPS/OLED

Memory trick: 'TN = Total Need for speed'

SMTP is the protocol used to send and relay email between mail servers, operating by default on TCP port 25.

• SMTP = Simple Mail Transfer Protocol
• Default port: TCP 25
• Used for sending, not retrieving, mail

Memory trick: 'S'MTP 'S'ends mail on port 25.

A system state where the storage drive (HDD or SSD) is constantly operating at maximum capacity, leading to severe performance bottlenecks.

• Often indicates a failing drive, struggling with read/write operations.
• Can be caused by background processes, malware, or driver issues.
• Leads to extreme system slowdowns, application crashes, and unresponsiveness.

Memory trick: When the disk is always busy at 100%, it's likely struggling to keep up, or even failing.

A symptom on mobile devices where the Wi-Fi activation switch is disabled and cannot be toggled, often indicating a hardware failure of the Wi-Fi module.

• Suggests the OS cannot initialize the Wi-Fi hardware.
• Other wireless functions (Bluetooth, cellular) typically remain functional.
• Often requires hardware repair or replacement of the Wi-Fi chip/module.

Memory trick: If the Wi-Fi switch is gray, the hardware inside has gone astray.

A condition where a mobile device's battery depletes quickly due to software activity, such as excessive background processes or applications, rather than a faulty battery or hardware.

• Battery health report often shows good capacity.
• Occurs even when the device appears idle or in sleep mode.
• Requires identifying and managing power-intensive software.

Memory trick: If the battery drains fast but is healthy, look for secret apps sucking power in the background.

A CPU may physically fit a socket but still require a motherboard BIOS/UEFI update to be properly recognized, especially across CPU generations.

• Always check motherboard QVL (Qualified Vendor List) before upgrading CPU
• BIOS update may be needed before installing newer CPU
• Same socket does not guarantee full compatibility

Memory trick: Socket fits ≠ system boots — check the BIOS first

A tone generator and probe (fox and hound) is a tool set used to trace and identify a specific cable among many unlabeled ones by sending and detecting an audible tone.

• Also called 'fox and hound'
• Generator sends signal, probe detects it
• Used for cable tracing, not performance testing

Memory trick: Fox and hound hunt down the right cable.

The cloud's ability to automatically scale resources up or down based on real-time demand.

• Key differentiator between cloud and traditional data centers
• Reduces cost by matching resources to actual need
• Often paired with auto-scaling groups and load balancers

Memory trick: Elastic like a rubber band—stretches and shrinks with demand.

A common issue in inkjet printers where dried ink blocks the tiny nozzles of the print head, leading to poor print quality, streaks, or missing colors.

• Often resolved by running the printer's built-in cleaning cycle.
• Can be prevented by regular printer use.
• Symptoms include streaky prints, blank lines, or incorrect colors.

Memory trick: Inkjet Ink Needs Clear Nozzles.

A hybrid cloud technique where workload automatically overflows from a private cloud to a public cloud during demand spikes, then returns when demand decreases.

• Requires hybrid cloud architecture
• Maintains performance during traffic spikes
• Reduces need to overprovision private infrastructure

Memory trick: When the private dam overflows, workload bursts into the public cloud river.

RAID 1 mirrors data across two drives; if one fails, the array remains functional on the surviving drive but loses fault tolerance until replaced.

• RAID 1 = mirroring, no parity
• Survives single drive failure
• Rebuild requires new drive + remirroring, not automatic parity recovery

Memory trick: Mirror, mirror on the wall — lose one, the twin covers all (for now).

SATA III (SATA 6Gb/s) is the third generation of the SATA storage interface, supporting a maximum theoretical throughput of 6 Gbps.

• SATA I = 1.5 Gbps
• SATA II = 3 Gbps
• SATA III = 6 Gbps (~600 MB/s real-world)

Memory trick: 1.5, 3, 6 — SATA speeds double each generation

A 6-pin or 8-pin power connector from a power supply unit (PSU) specifically used to provide additional electrical power to high-performance PCI Express (PCIe) graphics cards.

• Modern graphics cards often require one or more PCIe power connectors.
• A 6-pin connector provides up to 75 watts, an 8-pin up to 150 watts.
• Incorrectly connecting other power connectors can damage components.

Memory trick: PSU's 'C.G.S.M.' - CPU, Graphics, SATA, Molex.

WPS is a feature allowing easy wireless network joining via a push button or PIN, but its PIN method is vulnerable to brute-force attacks and should be disabled for security.

• Push-button or 8-digit PIN method for joining Wi-Fi
• PIN method vulnerable to brute-force attacks
• Best practice is to disable WPS on SOHO routers

Memory trick: 'WPS' = 'Weak PIN Security' — easy button, easy breach.

RG-6 is a coaxial cable with better shielding than RG-59, commonly used for cable TV and cable modem internet connections, typically terminated with F-connectors.

• Used for cable TV and cable internet service
• Terminated with F-connectors
• Has thicker shielding than older RG-59 cable

Memory trick: 'RG-6' rhymes with 'TV mix' — think cable television and internet.

The natural decline in a mobile device's battery capacity and ability to hold a charge over time, often leading to inaccurate charge reporting and sudden shutdowns.

• Lithium-ion batteries degrade with age and charge cycles.
• Symptoms include rapid, non-linear discharge and sudden shutdowns.
• Often results in the battery management system misreporting remaining charge.

Memory trick: A failing battery often 'lies' about its power level, then dies.

RAID 10 (1+0) combines mirroring and striping; usable capacity always equals half of the total raw capacity of all drives combined.

• Requires a minimum of 4 drives
• Usable capacity = (number of drives x drive size) / 2
• Offers both fault tolerance and improved read/write performance

Memory trick: 'Ten Takes Half' — RAID 10 always halves your raw total.

The imaging drum in a laser printer transfers toner to paper; scratches or debris on it cause a mark that repeats at a fixed interval equal to the drum's circumference.

• Repeating marks = drum defect, spacing reveals drum size
• Low toner causes fading, not repeating marks
• Drum is often part of a replaceable toner cartridge unit

Memory trick: 'Repeats Reveal the Drum.'

The maximum data transfer rate a video interface can support, determining the highest resolution and refresh rate combinations possible.

• Higher resolutions and refresh rates require greater bandwidth.
• Modern interfaces like DisplayPort and HDMI 2.0+ offer high bandwidth.
• Older interfaces like VGA and DVI have limited capabilities.

Memory trick: For high-res, 'Display' the 'Port' or 'High-Def' the 'Media'.

Reserved IPv4 address blocks used for internal networks that are not routed on the public internet.

• 10.0.0.0/8
• 172.16.0.0/12
• 192.168.0.0/16

Memory trick: '10, 172, 192' stay home, never roam.

Ghosting in a laser printer, characterized by faint repeated images down the page, is usually caused by a defective cleaning blade in the drum unit failing to remove residual toner.

• Faint image repeats down page
• Drum not fully cleaned
• Cleaning blade is part of drum unit
• Often requires drum replacement

Memory trick: Cleaning Blade is Bad: Ghosting is Glad.

Port 443 is the well-known TCP port used for HTTP Secure (HTTPS) traffic, encrypting data between client and server using TLS/SSL.

• HTTP uses port 80 (unencrypted)
• HTTPS uses port 443 (encrypted)
• TLS/SSL provides the encryption layer for HTTPS

Memory trick: '4-4-3, keep it secure like me' — HTTPS locks the door.

An MX (Mail Exchange) record in DNS specifies which mail server should receive email for a given domain, along with a priority value for multiple servers.

• Lower priority number = higher preference for mail delivery
• Points to a hostname, which must resolve via an A record
• Multiple MX records allow for backup mail servers

Memory trick: MX = 'Mail eXpress' — routes your email home.

Operating system features that allow users to control which applications can access the integrated webcam.

• Can block all camera access or specific app access.
• Often found in system settings under 'Privacy' or 'Security'.
• A common cause of a black webcam image even when hardware is functional.

Memory trick: Privacy settings often hide the camera's eye.

TCP port 80 is used for unencrypted web traffic using the HTTP protocol.

• HTTP = port 80 (unencrypted)
• HTTPS = port 443 (encrypted with TLS/SSL)
• Firewalls can block one port while allowing the other

Memory trick: HTTP ate(80) plain, HTTPS(443) locked it up.

An MDM feature that creates an isolated, encrypted container on a device to separate corporate apps/data from personal content, commonly used in BYOD environments.

• Enables selective/corporate-only remote wipe
• Keeps personal and corporate data logically separated
• Common in BYOD policies to protect both privacy and company data

Memory trick: 'Container keeps work in its own box'

A wireless technology (introduced in 802.11ac Wave 2) that allows an access point to send data to multiple compatible clients simultaneously rather than one at a time.

• Improves efficiency in high-density device environments
• Requires MU-MIMO-capable client devices to benefit fully
• Different from beamforming, which focuses signal direction to a single device

Memory trick: MU-MIMO = 'Multiple Users, Many Instant Outputs' at once.

Symptoms of a failing RAM module often include sporadic system freezes, 'STOP' errors (Blue Screen of Death), unexpected reboots, and data corruption.

• Inconsistent system behavior
• Often leads to BSODs or unexpected reboots
• Can cause data corruption

Memory trick: Random Access Memory makes random access errors.

Digital video connectors capable of transmitting high-resolution and high-refresh-rate signals, essential for modern displays.

• HDMI 2.1 and DisplayPort 1.4+ are current leading standards.
• Bandwidth determines maximum resolution and refresh rate support.
• Features like VRR and HDR also rely on sufficient bandwidth.

Memory trick: High Demands Need Dedicated Digital Data.

A process of planning and designing a wireless network to provide adequate signal coverage, data rates, and network capacity, while minimizing interference.

• Involves using specialized software and hardware to analyze the RF environment.
• Identifies existing Wi-Fi networks, signal strengths, and channel usage.
• Helps in optimal placement of APs and selection of non-overlapping channels.

Memory trick: When Wi-Fi slows down and drops, you need a survey to see what's jamming the airwaves.

The first step of the CompTIA troubleshooting methodology, involving gathering information from the user, identifying symptoms, and determining recent changes.

• Ask open-ended questions first
• Document symptoms and changes
• Avoid assumptions before gathering facts

Memory trick: "Investigate before you Innovate" — question first, fix second.

When a Windows client cannot obtain an IP address from a DHCP server, it self-assigns an address in the 169.254.0.0/16 range so it can still communicate on the local segment.

• Range: 169.254.0.1 to 169.254.255.254
• Indicates DHCP server unreachable or unavailable
• Device can only communicate with other APIPA devices on the same local segment

Memory trick: '169 means DHCP said no.'

UEFI Secure Boot verifies digital signatures on boot loaders and will prevent unsigned or improperly prepared USB installation media from booting, even if listed first in boot order.

• Secure Boot requires signed bootloaders
• Can block legitimate but unsigned USB installers
• Temporarily disabling Secure Boot often resolves the issue

Memory trick: Secure Boot is a bouncer — no signature, no entry, no boot.

POP3 (TCP 110) downloads and typically removes email from the server for single-device access; IMAP (TCP 143) keeps messages on the server for synchronized multi-device access.

• POP3 default port is 110; secure POP3 uses 995
• IMAP default port is 143; secure IMAP uses 993
• IMAP is preferred when accessing mail from multiple devices

Memory trick: POP pulls and pops it off the server; IMAP keeps it in mutual access.

A compact memory module format designed for laptops and other space-constrained devices.

• Smaller than standard DIMMs
• Common types: DDR3, DDR4, DDR5 SO-DIMM
• Installed at an angle then pressed flat to lock in

Memory trick: SO-DIMM: 'Small enough to fit in a Slim laptop'

SSH (Secure Shell) provides an encrypted method for remotely accessing a command-line interface, using TCP port 22.

• Default port: TCP 22
• Replaces insecure Telnet (port 23)
• Commonly used to manage Linux/Unix servers

Memory trick: SSH is Telnet's secure sibling — 22 not 23.

Error-Correcting Code (ECC) RAM is a type of computer memory that can detect and correct the most common kinds of internal data corruption.

• Crucial for servers and workstations requiring high data integrity and uptime.
• Uses parity bits and algorithms to identify and fix errors.
• Requires a motherboard and CPU that support ECC memory.

Memory trick: Memory Integrity Ensures Critical Computing.

A dead pixel never illuminates and appears black; a stuck pixel is locked on one color due to a transistor issue.

• Dead pixel = no power, black dot
• Stuck pixel = fixed color (often red/green/blue)
• Both are hardware defects, not software issues

Memory trick: Dead pixels are 'dark and gone'; stuck pixels are 'colorfully frozen'.

A DNS record type used for reverse lookups, mapping an IP address to its associated domain name.

• Opposite of an A record (forward lookup)
• Commonly used for anti-spam email verification
• Stored in the in-addr.arpa reverse DNS zone

Memory trick: PTR 'Points The Reverse' way, IP to name.

A swollen lithium battery indicates internal gas buildup and should be handled with extreme care, powered off, and never punctured or bent.

• Never puncture or bend a swollen battery
• Power off device immediately
• Dispose of swollen batteries per hazardous material guidelines

Memory trick: Swollen battery = sleeping bomb; power off, don't poke it.

A pen-like input accessory that communicates with a device's digitizer to provide precise, pressure-sensitive input.

• Requires digitizer support in the screen
• Offers pressure sensitivity for drawing/writing
• Differs from passive capacitive stylus which lacks pressure sensing

Memory trick: Active stylus = artist's precise pen for the digitizer canvas.

A saved point-in-time image of a VM's disk state, memory, and configuration that allows quick reversion if changes cause problems.

• Faster and smaller than a full clone
• Commonly used before updates or risky changes
• Multiple snapshots can create a chain, impacting performance

Memory trick: Snapshot a photo of the VM before it changes its outfit.

The process of checking a client's DHCP-assigned IP address details, particularly lease duration and expiration, to troubleshoot connectivity issues.

• DHCP leases grant an IP address for a specific time.
• Failure to renew a lease results in loss of network connectivity.
• `ipconfig /all` (Windows) or `ifconfig` (Linux/macOS) provides lease details.

Memory trick: To see your network 'ID' and 'lease' time, 'ipconfig /all' is prime.

A wiring error where two wires from different twisted pairs are used as if they were a matched pair, passing continuity tests but causing crosstalk and performance issues.

• Passes basic continuity, fails wire-map/certifier test
• Twisted pairs cancel noise; splitting pairs defeats this
• Causes crosstalk, intermittent errors, reduced speed

Memory trick: Twisted pairs dance together — split them up and they start stepping on each other's toes (crosstalk).

The process of seating a Land Grid Array (LGA) CPU into its motherboard socket, characterized by pins on the socket rather than the CPU.

• Requires careful alignment of CPU notches/markers with the socket.
• CPU should drop in with minimal force.
• Closing the retention arm locks the CPU into place.

Memory trick: Carefully Connect CPU Coolly.

The digitizer is the touch-sensing layer on a mobile device screen; when it fails, symptoms include ghost touches, unresponsive zones, and inaccurate tap registration.

• Digitizer is separate from the LCD/OLED display panel
• Common causes: physical damage, moisture, aging adhesive
• Symptoms: ghost touches, dead zones, misregistration

Memory trick: 'Ghost Touches = Ghost in the Digitizer.'

A punch-down tool is used to terminate individual wires into insulation displacement connector (IDC) slots on patch panels and keystone jacks, trimming excess wire automatically.

• Used with 110 or Krone blocks and keystone jacks
• Cuts excess wire during termination
• Different from crimpers, which terminate RJ45 plugs

Memory trick: Punch it down into the panel, crimp it onto the plug.

Video connection standards capable of transmitting high-bandwidth signals required for 4K, 8K, and high-refresh-rate monitors, often including HDR support.

• DisplayPort: High bandwidth, common for PC gaming.
• HDMI: Versatile, common for TVs/monitors, newer versions support high bandwidth.
• VGA/DVI: Older, limited bandwidth for modern displays.
• Bandwidth is key for resolution + refresh rate + color depth.

Memory trick: For high-refresh 4K, DisplayPort is the key, HDMI's good, but DP's for the PC.

A 15-pin flat connector used to provide electrical power to SATA hard drives and SSDs from a power supply unit.

• 15 pins.
• Supplies 3.3V, 5V, and 12V.
• Standard for all SATA devices.

Memory trick: Power for SATA? Think 15 pins, flat and neat, for your drive's electrical treat.

When a laptop's image is very dim but visible with a bright light source, the backlight (LED) or inverter (CCFL) supplying light to the LCD panel has likely failed.

• Flashlight test: dim faint image = backlight/inverter issue
• External monitor working normally rules out GPU
• LED backlights don't use inverters; CCFL backlights do

Memory trick: 'Flashlight Finds the Faint Backlight.'

When a 'No Boot Device Found' error occurs despite the boot drive being detected in BIOS/UEFI and the boot order being correct, it typically indicates a corrupted boot sector or Master Boot Record (MBR) on the drive.

• Drive is physically recognized
• Boot order is correct
• OS cannot initiate boot process
• Often requires boot repair tools

Memory trick: Boot Records are Broken, so Repair Boot.