CompTIA A+ Core 1 (220-1201) flashcards

A memory architecture that doubles the data bandwidth by allowing the memory controller to access two memory modules simultaneously.

• Requires two (or four) identical RAM modules.
• Modules must be installed in specific, paired slots (often color-coded).
• Significantly improves performance for memory-intensive tasks.

Memory trick: Channels Carry Computing Capacity Clearly.

DHCP automatically assigns IP addresses, subnet masks, default gateways, and DNS server addresses to devices joining a network.

• Uses UDP ports 67 (server) and 68 (client)
• Process: Discover, Offer, Request, Acknowledge (DORA)
• Leases can expire and be renewed

Memory trick: DORA the Explorer finds your IP address for you.

Impact printers use a pin-based print head striking an inked ribbon against paper, enabling multi-part carbonless form printing and durability in harsh environments.

• Only printer type that can print multi-part forms in one pass
• Common in warehouses, invoicing, and industrial settings
• Print head/ribbon wear are common maintenance points

Memory trick: Impact printers punch through paper stacks like a tiny typewriter army

A display issue where the screen briefly goes black or loses signal, then returns to normal, often caused by loose connections or failing video hardware.

• Can be random or triggered by slight movement/vibration.
• Often related to the graphics card, its connection, or the display cable.
• Symptoms include flickering, brief black screens, or signal drops.

Memory trick: When the screen blinks out randomly, check the GPU's seat or its cable.

A component in a liquid cooling system that dissipates heat from the circulating coolant into the surrounding air, typically using fins and fans.

• Transfers heat from liquid to air.
• Usually consists of fins and a fan.
• Crucial for maintaining optimal CPU temperatures.

Memory trick: Liquid flows, heat goes, radiator knows.

Some ISPs block inbound traffic on common server ports (like 80, 25) on residential/consumer accounts to discourage self-hosting, which can cause port forwarding to appear broken even when configured correctly.

• Port forwarding maps external port to internal IP:port on router
• ISP-level blocks occur upstream of the router and can't be fixed locally
• Testing with a port-checking tool from outside the network helps confirm ISP blocking

Memory trick: Correct config but no access outside? Blame the ISP's gate first.

A cloud characteristic where resource usage is automatically monitored and billed based on actual consumption, like a utility.

• Pay only for what is used
• Enables transparent billing
• One of five NIST cloud essential characteristics

Memory trick: Cloud bills like electricity — pay for what you use.

A threaded, screw-on coaxial connector used with RG-6 cable for cable television and cable internet service.

• Used by cable modems and cable TV boxes
• Threaded design provides a secure, weatherproof connection
• Different from BNC, which uses a twist-lock mechanism

Memory trick: F for fastened-on, screw it tight for cable TV.

Network Time Protocol uses UDP port 123 to synchronize clocks between computers and network devices.

• Critical for certificate validation and Kerberos authentication
• Uses UDP for lightweight, connectionless communication
• Clock drift can cause security and logging inconsistencies

Memory trick: NTP: one-two-three, keep the clocks in harmony.

DNS uses port 53 (UDP for queries, TCP for zone transfers/large responses) to translate domain names into IP addresses.

• UDP 53 for standard lookups
• TCP 53 for zone transfers or large replies
• Essential for resolving domain names to IPs

Memory trick: '53 keys' unlock the name-to-number door.

RAID 5 stripes data with distributed parity across all disks, sacrificing one disk's worth of capacity for fault tolerance.

• Formula: usable = (n-1) × drive size
• Requires minimum 3 drives
• Can survive failure of exactly one drive

Memory trick: RAID 5 = lose one drive's worth to parity, keep the rest

An internal laptop card that provides cellular data connectivity, requiring a SIM card for network authentication just like a smartphone.

• Installed in a dedicated mini-PCIe/M.2 slot
• Requires SIM card for carrier authentication
• Uses its own antenna cables separate from Wi-Fi antennas

Memory trick: 'No SIM, no signal'

A cloud characteristic allowing consumers to automatically provision computing resources as needed without human interaction with the provider.

• One of the core NIST cloud characteristics
• Achieved via web portals or APIs
• No provider staff involvement required

Memory trick: Self-serve means no waiter needed — click and get your resource.

Thermal printers require paper with a heat-sensitive coating facing the thermal print head; loading it backward results in blank prints.

• No ink or toner is used—image is created by heat
• Paper has one heat-sensitive coated side
• Self-test blank pages point to paper orientation, not driver issues

Memory trick: Flip the roll if the receipt shows nothing at all

A situation where virtual machines are created faster than they can be managed or decommissioned, resulting in unused VMs wasting resources and licenses.

• Caused by lack of lifecycle management
• Wastes storage, CPU, and licensing costs
• Mitigated by VM inventory audits and governance policies

Memory trick: Forgotten VMs become zombie machines haunting your host.

A Mobile Device Management feature that remotely erases data from a lost or stolen device to prevent unauthorized access.

• Can wipe entire device or just corporate container
• Triggered from MDM admin console
• Critical step in device loss/theft incident response

Memory trick: Stolen phone? Wipe it clean before thieves peek in.

In the 2.4 GHz Wi-Fi band, channels 1, 6, and 11 are the only three non-overlapping channels. Using these channels, spaced appropriately, helps minimize co-channel interference in dense environments.

• 2.4 GHz has 11-13 channels depending on region
• Each channel is 20 MHz wide
• Channels 1, 6, 11 are 25 MHz apart, preventing overlap
• Using overlapping channels causes signal degradation

Memory trick: One Six Eleven: No Overlap Heaven.

An enhanced twisted-pair Ethernet cable standard supporting 10Gbps speeds at full 100-meter distances with reduced crosstalk.

• Supports 10GBASE-T at 100m
• Improved shielding vs Cat6
• Backward compatible with Cat5e/Cat6 devices

Memory trick: '6a' Adds Armor for full 10G at 100m.

A hypervisor installed as an application on top of a host operating system, allowing VMs to run alongside normal desktop use.

• Examples: VMware Workstation, Oracle VirtualBox, Parallels
• Easier to set up on existing desktops/laptops
• More overhead than Type 1 due to host OS layer

Memory trick: Type 2 = 'Two layers' — OS then hypervisor.

RAID 5 stripes data with distributed parity across at least three disks, allowing the array to survive and rebuild after a single disk failure.

• Requires minimum 3 disks
• Tolerates exactly 1 disk failure
• Rebuild uses parity data to reconstruct lost disk contents

Memory trick: 'Parity Patches the Puzzle' — one missing piece can be rebuilt.

Small, metal or plastic spacers used to mount a motherboard to a computer case, providing clearance and preventing electrical shorts.

• Elevate the motherboard from the chassis.
• Prevent short circuits.
• Typically threaded for screws.

Memory trick: Standoffs stand off shorts.

80 PLUS certification measures a power supply's energy efficiency at various load levels, with tiers ranging from White (lowest) to Titanium (highest).

• Order: White < Bronze < Silver < Gold < Platinum < Titanium
• Higher tiers waste less energy as heat
• Titanium requires ~90%+ efficiency across most loads

Memory trick: Winning Bronze Sprinters Go Platinum Then Titanium (climbing tiers)

A technology that hosts desktop operating systems as virtual machines in a centralized data center and streams them to end-user devices.

• Data stays centralized, improving security and compliance
• Users can access identical desktops from any thin client
• Requires strong network bandwidth for a good user experience

Memory trick: VDI = 'Virtual Desktop In the data center' — data never leaves.

A S.M.A.R.T. attribute tracking sectors remapped due to physical defects; a rising count signals impending drive failure.

• S.M.A.R.T. = Self-Monitoring, Analysis, and Reporting Technology
• Rising reallocated sectors predict failure
• Best response: back up data and replace drive

Memory trick: S.M.A.R.T. drives whisper before they die — listen and back up!

The critical step of correctly aligning and placing a CPU into its motherboard socket, ensuring pins (or pads) make proper contact without force before securing it.

• Align triangle/dot on CPU with socket.
• CPU should drop in with minimal force.
• Excessive force indicates improper seating or alignment.
• Can bend pins and damage CPU/socket.

Memory trick: Align the triangle, then gently drop in; force means trouble, a bent pin's a sin.

Different configurations of multiple hard drives to improve performance, provide redundancy, or both, with varying trade-offs.

• RAID 0: Striping, no redundancy.
• RAID 1: Mirroring, 50% capacity loss.
• RAID 5: Striping with parity, single drive fault tolerance, N-1 capacity.
• RAID 10: Striping and mirroring, N/2 capacity, high fault tolerance.

Memory trick: Redundancy and Capacity: Choose wisely for your data's destiny.

A standardized six-step process technicians follow to resolve IT issues consistently: identify problem, establish theory, test theory, establish plan of action, implement solution, and document.

• Step 1: Identify the problem (question user, reproduce issue)
• Step 2: Establish a theory of probable cause
• Final step: Document findings, actions, and outcomes

Memory trick: 'I Eat Tacos To Impress Vegans' = Identify, Establish theory, Test theory, plan of action, Implement, Verify/document.

Bluetooth devices are categorized by power class, which determines typical wireless range.

• Class 1: ~100 meters, higher power
• Class 2: ~10 meters, most common consumer devices
• Class 3: ~1 meter, rarely used

Memory trick: Class 2 = '2 rooms away'—about 10 meters.

Telnet is a legacy protocol that provides unencrypted command-line remote access to network devices over TCP port 23.

• Uses TCP port 23
• Transmits data, including credentials, in plaintext
• Largely replaced by SSH (port 22) for security

Memory trick: 'Telnet' = Terrible Encryption, Lame Network — always Not Trustworthy.

LC (Lucent Connector) is a small-form-factor fiber optic connector with a push-pull latch, enabling higher density than SC or ST connectors.

• Small form factor, high density
• Push-pull latching mechanism
• Common in modern fiber patch panels

Memory trick: 'L'C is 'L'ittle, so more fit on a panel.

A laptop FRU that combines the keyboard, palm rest, and often the touchpad into a single replaceable part.

• Common in ultrabooks to save space
• Requires full assembly replacement even for a single failed key
• Reduces disassembly complexity but increases part cost

Memory trick: Top cover = keyboard's whole neighborhood, not just one house.

A DNS record type that maps an alias domain name to another canonical domain name instead of directly to an IP address.

• Simplifies maintenance when the underlying IP changes
• Cannot coexist with other record types for the same name
• Commonly used for subdomains like 'www' or 'shop'

Memory trick: CNAME chains a name to a name, not a number.

A cloud deployment model that combines private and public cloud infrastructures, interconnected to allow data and application portability between them.

• Enables 'cloud bursting' to handle demand spikes
• Sensitive data can stay on private infrastructure
• Requires reliable connectivity between environments

Memory trick: Hybrid = 'Half private, half public, bridged together.'

A DMZ host setting on a SOHO router forwards all incoming, unsolicited internet traffic to one specified internal device.

• Exposes all ports to one device
• Reduces need for manual port forwarding
• Increases risk to the exposed device

Memory trick: DMZ = 'Dump My Zone' traffic onto one device.

The fifth step of the CompTIA troubleshooting methodology, performed after implementing a solution, in which the technician confirms the entire system works correctly and applies preventive measures if needed.

• Comes after 'implement the solution'
• Involves testing beyond the immediate reported symptom
• Precedes the final documentation step

Memory trick: 'Fix it, then Flex it' — test the whole system after implementing.

Identifying a network configuration error where two connected devices operate at different duplex settings, causing performance issues.

• Leads to excessive collisions, retransmissions, and slow speeds.
• Symptoms are intermittent connectivity, poor throughput.
• Best diagnosed by observing collision rates with a network analyzer.

Memory trick: When the network's ghosting, a 'sniffer' will show what's boasting.

An organic light-emitting diode display where each pixel emits its own light, allowing true blacks and vivid color but with burn-in risk.

• No backlight needed; pixels self-illuminate
• Excellent contrast and color accuracy
• Susceptible to burn-in with static images over time

Memory trick: OLED = 'Own Light, Extreme Drama' — vivid but risky

A reserved IPv4 address used to test a device's own network stack without requiring physical network connectivity.

• Entire 127.0.0.0/8 range is reserved for loopback
• IPv6 equivalent is ::1
• Successful ping confirms TCP/IP stack works regardless of NIC/cable status

Memory trick: '127, look in the mirror' — pinging yourself.

M.2 slots and drives use notched keys (B, M, or B+M) to indicate supported interfaces like SATA or PCIe lanes; mismatched keys prevent proper installation.

• B key = up to PCIe x2 or SATA
• M key = up to PCIe x4 (NVMe)
• B+M key on slot supports both B and M keyed drives, but only up to the slot's actual lane support

Memory trick: B and M keys must match the lock, or the drive won't turn on

A router function that translates private internal IP addresses to a single public IP address, allowing multiple devices to share one internet connection.

• Conserves public IPv4 addresses
• Tracks port/session mappings to route return traffic correctly
• Standard feature in SOHO routers

Memory trick: NAT lets many private faces share one public mask.

A power supply unit that cannot provide the necessary stable power to fully initiate and sustain the computer's boot sequence.

• Symptoms include fans briefly spinning, lights flashing, then immediate shutdown.
• Often intermittent and worsens over time.
• Can be caused by component degradation within the PSU.

Memory trick: If the power flickers and dies, the 'supply' is telling lies.

Hardware features (Intel VT-x, AMD-V) that must be enabled in BIOS/UEFI to allow hypervisors to run VMs efficiently, especially 64-bit guests.

• Often disabled by default in BIOS/UEFI
• Required for most modern hypervisors
• Check CPU spec sheet to confirm support

Memory trick: Unlock the CPU's hidden virtualization switch in BIOS before VMs will run.

A thin, seven-pin cable used to connect SATA (Serial ATA) storage devices, such as hard drives and SSDs, to the motherboard for data transfer.

• Replaced the wider PATA (IDE) ribbon cables.
• Transmits data serially (one bit at a time).
• Distinct from the 15-pin SATA power cable.

Memory trick: Storage Connections Seek Appropriate Standards.

SNMP is a protocol used to monitor and manage network devices such as routers and switches by querying device agents over UDP port 161.

• Uses UDP port 161 for agent queries
• Port 162 is used for SNMP traps (alerts)
• Common in centralized network monitoring systems

Memory trick: 'SNMP 161' — think 'Sixteen-One' devices reporting status to one manager.

Random reboots, blue screen errors, or system freezes caused by a power supply unit that cannot provide stable or sufficient power, especially under high demand.

• Symptoms worsen under heavy CPU/GPU load.
• Can be intermittent and difficult to diagnose.
• Often requires testing or replacement of the PSU.

Memory trick: When the system crashes and reboots under stress, if it's not heat, it's often the power struggling.

Dual-band Wi-Fi operates on two distinct radio frequency bands, 2.4 GHz and 5 GHz, each with unique advantages and disadvantages in terms of range, speed, and interference.

• 2.4 GHz offers longer range and better penetration but is more susceptible to interference.
• 5 GHz offers higher speeds and less interference but has a shorter range and struggles with obstacles.
• Modern WAPs and devices support both bands to optimize performance.

Memory trick: Wi-Fi bands: '2.4' for 'Range', '5' for 'Speed' and 'Space'.

An IPv6 link-local address, beginning with fe80::, is automatically assigned to every interface and is only valid for communication within the local network segment.

• Prefix range: fe80::/10
• Not routable beyond local subnet
• Every IPv6-enabled interface has one automatically

Memory trick: fe80 stays home — never leaves the local link.

The process of correctly seating and securing a Central Processing Unit (CPU) onto a motherboard's socket.

• Requires careful alignment with the socket's keying mechanism.
• Retention arm/lever secures the CPU both physically and electrically.
• Thermal paste and a cooler are essential for heat dissipation.

Memory trick: CPU 'S.A.F.E.' - Socket, Arm, Fan, Electrical.

Dedicated power connectors (6-pin or 8-pin) from the PSU to provide supplemental power to high-performance graphics cards.

• 6-pin provides up to 75W, 8-pin provides up to 150W.
• Graphics cards also draw up to 75W from the PCIe slot itself.
• Using adapters for high-power cards can be unsafe due to current limitations.

Memory trick: Power Properly Prevents Problems.

A display technology offering accurate color reproduction and wide viewing angles, favored for creative work.

• Better color accuracy than TN
• Wider viewing angles than TN
• Often slightly slower response time than TN, but negligible for photo editing

Memory trick: IPS = 'Incredibly Precise Screen' for color work.

A configured data usage limit for a mobile hotspot connection, tracked in MB/GB to prevent overage charges.

• 1 GB = 1024 MB (or approximated as 1000 MB for billing)
• Streaming and downloads both count toward the cap
• MDM/carrier apps often alert users near the cap

Memory trick: Add up the bytes, then subtract from the cap.

Software utilities designed to test the integrity and functionality of a computer's Random Access Memory (RAM) modules.

• Identifies errors in memory that can cause system instability, crashes, and BSODs.
• Examples include MemTest86 for bootable diagnostics and Windows Memory Diagnostic.
• Essential for troubleshooting issues that arise after RAM installation or upgrade.

Memory trick: If 'new RAM' causes crashes, 'test' its health before more dashes.

When a computer powers on (fans, lights) but has no video output and no POST beeps, even after reseating RAM/GPU, it strongly indicates a failure of the CPU or motherboard, as these are critical for initiating the power-on self-test.

• Power present, but no boot sequence
• RAM/GPU ruled out
• CPU and motherboard are core for POST
• Often requires component replacement

Memory trick: CPU or Motherboard: Core Parts are Broken.

Distorted, pixelated, or freezing webcam video across multiple applications typically indicates an issue with the webcam's drivers, which facilitate communication between the hardware and the operating system.

• Affects multiple applications
• Persists after restart
• Drivers are crucial for hardware function
• Hardware itself is less likely if intermittent

Memory trick: Drivers Drive the Display, Don't Delay.

A cloud model where the provider delivers a complete, ready-to-use application to end users over the internet.

• Examples: Google Workspace, Microsoft 365, Salesforce
• No infrastructure or platform management by the customer
• Accessed via browser or thin client

Memory trick: SaaS = 'Software already Set up.'

A larger motherboard form factor (Extended ATX) designed for high-end systems, offering increased expansion capabilities, more RAM slots, and enhanced power delivery.

• Dimensions are typically 12 x 13 inches (305 x 330 mm).
• Common in server, workstation, and enthusiast gaming builds.
• Supports multiple GPUs, high-core count CPUs, and extensive RAM configurations.

Memory trick: Many Sizes Are The X-factor.

A security step where a numeric code is displayed and entered/confirmed on both devices to authenticate a Bluetooth connection.

• Prevents unauthorized device pairing
• Sometimes called PIN pairing
• Required before data can be exchanged over Bluetooth

Memory trick: No passkey, no pairing — like a secret handshake

The process of safely handling a RAID 5 array where one drive has failed and another is showing signs of impending failure, prioritizing data integrity.

• RAID 5 can only tolerate a single drive failure.
• Two failures mean complete data loss.
• Immediate data backup is crucial before attempting repairs.

Memory trick: When RAID 5 is one drive from disaster, backup first, then fix.

A cloud model that provides a managed runtime environment, development tools, and databases so developers can build applications without managing underlying infrastructure.

• Examples: Microsoft Azure App Service, Google App Engine, Heroku
• Provider manages OS, runtime, and patching
• Ideal for rapid application development

Memory trick: PaaS = 'Platform provided, just add code.'

2.4GHz wireless signals travel farther and penetrate obstacles better but offer lower maximum throughput; 5GHz offers higher throughput but shorter range and weaker penetration.

• Lower frequency = longer range, better penetration, lower speed
• Higher frequency = shorter range, more interference susceptibility to obstacles, higher speed
• 2.4GHz has more channel overlap and interference from other devices

Memory trick: Low frequency travels far but slow; high frequency is fast but frail.