220-1201 — CompTIA A+ Core 1 Cheat Sheet

Last revised: September 16, 2026

Cheat sheet: independent review for CompTIA A+ Core 1 (220-1201): hardware, mobile, networking, virtualization, cloud, printers, and troubleshooting.

Use the tables for a quick pre-exam check. Expand a topic’s notes for explanations, examples, and additional distinctions.

Scope and study context

Core 1 questions often ask you to:

Identify a component, connector, cable, or port from a scenario.
Choose the best first step in troubleshooting.
Distinguish similar technologies: DNS vs. DHCP, M.2 vs. NVMe, WPA2 vs. WPA3, laser vs. inkjet, NAT vs. bridged VM networking.
Recommend hardware or network changes for a user requirement.
Interpret common symptoms without over-fixing the problem.

Scan the tables first. Ports, connectors, wireless standards, storage types, and troubleshooting symptoms are common scenario anchors.
Practice decision rules. Many questions ask for the “best,” “first,” or “most likely” answer.
Use question-bank practice after each section. Do not just memorize terms; practice applying them to support tickets.
Review missed explanations carefully. A missed A+ Core 1 question often comes from confusing two similar technologies.

Practical target: after reviewing a topic, you should be able to recognize it from symptoms, identify compatible components, and choose the next troubleshooting action.

High-Yield Decision Traps

Trap	Exam-safe distinction
M.2 means NVMe	M.2 is a form factor. M.2 drives can use SATA or NVMe/PCIe.
RAID is backup	RAID improves availability or performance; it does not replace backups.
USB-C means Thunderbolt	Thunderbolt may use USB-C, but not every USB-C port supports Thunderbolt.
169.254.x.x means Internet outage	It usually means APIPA: the client did not get DHCP configuration.
DNS fixes IP assignment	DNS resolves names. DHCP assigns IP configuration.
5 GHz is always better	5 GHz is faster/cleaner at shorter range; 2.4 GHz penetrates farther and is more crowded.
MAC filtering is strong security	It is weak; MAC addresses can be spoofed. Use WPA2/WPA3 and strong credentials.
Snapshot is a backup	VM snapshots are short-term rollback points, not full backup strategy.
Laser streaks always mean toner	Streaks can be toner, drum, fuser, transfer roller, or contamination.
Slow PC always needs RAM	Check storage, malware, startup apps, overheating, CPU load, and failing hardware.

Hardware Reference

Motherboard, CPU, Firmware, and Expansion

Area	Know for the exam	Common troubleshooting clue
Form factor	ATX, microATX, Mini-ITX affect case size, slots, ports, and PSU fit.	Board does not line up with standoffs or I/O shield.
CPU socket	CPU must match motherboard socket and chipset support.	No POST after CPU upgrade.
Chipset	Determines supported CPU family, RAM type, expansion, storage, and I/O features.	Feature present on CPU but unavailable on board.
UEFI/BIOS	Firmware initializes hardware, stores boot order, exposes hardware settings.	Wrong boot order, disabled device, outdated firmware.
CMOS battery	Maintains firmware settings and clock when powered off.	Time/date resets; BIOS settings lost.
TPM	Hardware/firmware root for security features.	Security feature unavailable or device fails compliance check.
Secure Boot	Helps ensure trusted bootloaders.	Alternate OS or boot media may fail until settings are adjusted.
PCIe	Expansion bus for GPUs, NICs, storage adapters, capture cards.	Card needs correct slot, power, driver, and clearance.
Cooling	Heat sink, fan, thermal paste, airflow.	Random shutdowns, thermal throttling, fan noise.

Notes and examples

RAM Selection and Symptoms

Concept	Practical reference
DIMM vs. SO-DIMM	DIMM is common in desktops/servers; SO-DIMM is common in laptops and small systems.
DDR generations	DDR versions are not physically interchangeable. Match board support.
Speed compatibility	RAM may run at the highest mutually supported speed of board/CPU/modules.
Capacity support	Check motherboard and OS support; avoid mixing unsupported sizes or types.
Dual-channel	Install matched modules in correct paired slots for performance.
ECC	Error-correcting memory; common in workstations/servers, requires platform support.
Symptoms of bad RAM	BSOD/kernel panic, random reboots, application crashes, failed memory diagnostics, no POST.

Storage Selection Matrix

Storage type	Choose when	Strengths	Limitations / traps
HDD	Low-cost bulk storage, archives, secondary drive.	High capacity per cost.	Mechanical failure, slower latency, vibration sensitivity.
SATA SSD	General PC upgrade, older systems, predictable compatibility.	Much faster than HDD; simple replacement path.	Limited by SATA interface.
NVMe SSD	High-performance boot/application drive.	Very low latency; PCIe performance.	Requires compatible M.2/PCIe support; heat may matter.
External USB drive	Portable backup, transfer, offline storage.	Easy and removable.	Can be lost, damaged, or disconnected.
NAS	Shared storage for multiple users/devices.	Centralized access, often supports RAID and permissions.	Network-dependent; still needs backup.
Optical drive	Legacy media, archival discs, installation media.	Useful for older environments.	Less common; slower and lower capacity.

RAID Cheat Sheet

RAID level	Minimum drives	Main purpose	Fault tolerance	Trap
RAID 0	2	Performance/striping	None	One failed drive can lose array data.
RAID 1	2	Mirroring	Can survive one drive failure in a pair	Capacity is reduced by mirroring.
RAID 5	3	Striping with parity	Can survive one drive failure	Rebuild stress can expose other failures.
RAID 6	4	Striping with dual parity	Can survive two drive failures	Accounts for two drives of parity capacity with equal-size disks.
RAID 10	4	Mirrored stripes	Good performance and redundancy	Requires more drives; not the same as RAID 0+1 in all failure cases.

Power and Internal Connectors

Connector/component	Used for	Exam clue
24-pin ATX	Main motherboard power.	System will not power correctly if not seated.
4/8-pin CPU power	CPU power near socket.	Fans may spin but system may not POST if missing.
PCIe power	Dedicated GPU or high-power expansion card.	GPU powers on partially or reports insufficient power.
SATA data	Connects SATA drives to motherboard.	Thin data cable; one drive per port.
SATA power	Powers SATA drives.	Wider power connector from PSU.
Molex	Legacy peripheral power.	Older fans/drives/adapters.
Front-panel headers	Power switch, reset, LEDs, audio, USB.	Case buttons or front USB/audio do not work.
Fan headers	CPU/system fans.	Incorrect header can trigger fan warnings.

External Ports and Connectors

Connector	Carries	Typical use	Trap
USB-A	Data/power	Keyboards, mice, flash drives.	Orientation-specific.
USB-C	Data/power/video depending on support	Modern laptops, phones, docks.	Connector shape does not guarantee protocol/features.
Thunderbolt	High-speed data, video, docks, storage	Docking stations, external GPUs, displays.	Often uses USB-C connector but requires Thunderbolt support.
HDMI	Digital audio/video	TVs, monitors, projectors.	Common for consumer displays.
DisplayPort	Digital audio/video	PCs, monitors, daisy-chaining in supported setups.	Common in business/PC displays.
VGA	Analog video	Legacy projectors/monitors.	No audio; analog quality issues.
DVI	Digital/analog variants	Older monitors.	Different pin layouts and capabilities.
RJ-45	Ethernet	Wired LAN.	Looks larger than RJ-11.
RJ-11	Telephone/DSL	Phone lines.	Not Ethernet.
3.5 mm audio	Analog audio	Headsets, speakers, microphones.	Combo jacks may need TRRS support.

Display and Peripheral Issues

Symptom	Likely causes	First checks
No display	Power, cable, input source, GPU, RAM, monitor failure.	Verify power/input, reseat cable, test known-good monitor/cable.
Dim laptop screen	Brightness, backlight, display cable, older inverter, panel failure.	Adjust brightness, external display test.
Flicker/artifacts	Cable, refresh rate, GPU driver, overheating GPU, failing monitor.	Reseat/replace cable, check temperature, update/rollback driver.
Touchscreen inaccurate	Calibration, driver, digitizer damage.	Clean screen, recalibrate, check driver.
Keyboard keys fail	Debris, liquid damage, loose ribbon cable, keyboard failure.	External keyboard test.
Mouse/touchpad erratic	Dirty sensor, surface issue, driver, palm rejection, battery.	Clean/test on different surface; check settings.

Motherboard and Expansion Review

Component	Key Idea	Watch For
CPU socket	Must match CPU family and board	Physical compatibility matters
Chipset	Determines supported features	CPU support, PCIe lanes, RAM type
RAM slots	Must support correct RAM generation and speed	DDR generations are not interchangeable
PCIe slots	Used for GPUs, NICs, storage adapters, capture cards	Larger slots can often support smaller cards physically, but performance depends on lanes
M.2 slot	Used for SSDs and sometimes wireless cards	M.2 keying and protocol matter
SATA ports	Connect SATA SSDs, HDDs, optical drives	Slower than modern NVMe
Front-panel headers	Power switch, reset, LEDs, USB, audio	Miswiring can cause “dead” front-panel behavior
CMOS/UEFI firmware	Hardware initialization and configuration	Boot order, TPM, virtualization support

CPU Review

Concept	Cheat Sheet
Cores	Physical processing units
Threads	Logical execution paths
Clock speed	Cycles per second; not the only performance factor
Cache	Fast memory inside/near CPU
Integrated GPU	Graphics built into CPU or chipset platform
Virtualization support	Required or recommended for many VM use cases
Thermal design	CPU requires correct cooling and thermal paste

RAM Review

Term	Meaning	Common Mistake
DIMM	Desktop memory module	Confusing with laptop memory
SO-DIMM	Laptop/small-form memory module	Installing wrong form factor
DDR generations	DDR3, DDR4, DDR5, etc.	Assuming different generations fit
ECC	Error-correcting memory	Often used in servers/workstations
Dual-channel	Matched memory channels improve performance	Installing mismatched modules poorly
Speed/latency	Performance characteristics	Board/CPU may run RAM below rated speed

Storage Review

Storage Type	Strengths	Weaknesses / Exam Clues
HDD	Large capacity, lower cost	Mechanical failure, slow access, noise
SATA SSD	Faster than HDD, common upgrade	Limited by SATA interface
NVMe SSD	Very fast, uses PCIe	Requires compatible M.2/PCIe support
Optical drive	Legacy media, recovery discs	Less common in modern systems
External USB storage	Portable backup/transfer	Cable, port, or power limitations
NAS	Network-based shared storage	Depends on network access and permissions

HDD vs SSD Symptoms

Symptom	More Likely Cause
Clicking, grinding, long seek delays	HDD mechanical failure
Slow boot on old system	HDD bottleneck or failing drive
System no longer detects drive	Cable, port, controller, drive failure, or firmware setting
Fast boot improvement after upgrade	HDD replaced with SSD
Sudden read/write errors	Drive failure, file system issue, or storage controller problem

RAID Cheat Sheet

RAID Level	Minimum Drives	Main Benefit	Main Risk / Note
RAID 0	2	Performance / combined capacity	No fault tolerance
RAID 1	2	Mirroring / redundancy	Capacity efficiency is lower
RAID 5	3	Striping with parity	Can tolerate one drive failure
RAID 6	4	Striping with dual parity	Can tolerate two drive failures
RAID 10	4	Mirroring + striping	Good performance and redundancy, more drives required

Select a RAID level from the required drive-failure tolerance, available drives, usable capacity, and workload. Performance alone does not distinguish every level, and RAID is not a backup.

Startup and Boot Symptoms

Symptom	Likely Area
No POST	Power, motherboard, CPU, RAM
Beep codes/diagnostic lights	Check vendor diagnostics meaning
Boot device not found	Drive, boot order, cable, OS boot files
Continuous reboot	Power, overheating, OS, driver, RAM
Blue screen/kernel panic	Driver, hardware, memory, storage, OS
Date/time resets	CMOS battery or firmware settings
Slow boot	Startup apps, storage, malware, failing drive, low RAM

Performance Symptoms

Symptom	Likely Cause
System slow overall	Low RAM, slow storage, background processes, malware, overheating
Slow only on network resources	Network, DNS, server, wireless, bandwidth
Freezes under heavy load	Heat, RAM, PSU, driver
Loud fans	Heat, dust, fan curve, failing fan
App-specific slowness	Application, storage, memory, compatibility

Hardware Replacement Decision Points

If the Scenario Says…	Think About…
“After adding RAM, system will not boot”	Compatibility, seating, slot order
“After moving PC, no display”	Loose cable/card/RAM
“After power outage”	PSU, surge damage, file system corruption
“After installing GPU”	PSU wattage, PCIe power, drivers
“After BIOS/UEFI change”	Boot order, secure boot, storage mode
“Only one USB device fails”	Device/cable/port compatibility
“All USB devices fail”	Controller, driver, BIOS/UEFI, power

Mobile and Laptop Reference

Laptop Field-Service Items

Component	What to remember
Battery	Use compatible replacement; swollen batteries are safety issues.
RAM	Often SO-DIMM; some systems have soldered RAM.
Storage	May be 2.5-inch SATA, M.2 SATA, or M.2 NVMe.
Wi-Fi/Bluetooth card	Internal antenna leads must be reconnected correctly.
Keyboard	Often ribbon-cable connected; model-specific replacement.
Screen assembly	Panel, bezel, hinges, webcam, microphone, Wi-Fi antennas may be integrated.
DC jack	Loose/broken charging port can mimic bad adapter or battery.
Cooling assembly	Dust, failed fan, poor thermal paste cause throttling/shutdowns.

Notes and examples

Mobile Connectivity and Sync

Feature	Use	Troubleshooting clue
Cellular	Carrier network data/voice.	Check signal, SIM/eSIM, APN/carrier settings, airplane mode.
Wi-Fi	Local network/Internet.	Forget/rejoin network, verify password, DHCP, captive portal.
Bluetooth	Short-range peripherals.	Pairing mode, distance, battery, interference, remove/re-pair.
NFC	Tap-to-pair, mobile payments, badges.	Very short range; case or disabled setting can interfere.
Hotspot/tethering	Share mobile data to other devices.	Carrier plan, battery drain, data limits, Wi-Fi password.
GPS/location	Navigation, device location.	Permissions, indoor reception, battery-saving mode.
Cloud sync	Contacts, photos, files, settings.	Account sign-in, storage availability, network, sync toggles.
Local sync	Cable or local application sync.	Cable quality, trust prompt, drivers, app version.

Mobile Symptoms

Symptom	Likely cause	Best first actions
Rapid battery drain	Bad battery, weak signal, background apps, high brightness, GPS/Bluetooth.	Check battery usage, disable unnecessary services, test charger.
Won’t charge	Cable, adapter, port debris/damage, battery, charging IC.	Try known-good charger/cable, inspect port carefully.
Overheating	Heavy app, poor ventilation, battery fault, direct sun, failing hardware.	Close apps, remove case, cool down safely.
No Bluetooth pairing	Device not discoverable, already paired, low battery, compatibility.	Reboot, forget pairing, pair again.
App crashes	App bug, OS version, storage full, corrupted cache/data.	Update app/OS, clear cache, reinstall if needed.
No mobile data	Airplane mode, SIM/eSIM issue, APN/carrier outage, plan issue.	Toggle data, check SIM/eSIM, verify carrier settings.

Networking Reference

Core Network Services and Devices

Item	Function	Choose/identify when
Modem/ONT	Connects premises to ISP medium.	Cable/DSL/fiber handoff issue.
Router	Routes between networks; often does NAT and DHCP in SOHO.	Need default gateway or Internet sharing.
Switch	Connects devices within a LAN using MAC addresses.	Need more wired LAN ports.
Wireless AP	Provides Wi-Fi access to wired network.	Need wireless coverage, not routing.
Firewall	Allows/blocks traffic based on rules.	Need traffic filtering/security boundary.
UTM/security appliance	Combines firewall and security services.	Need consolidated gateway filtering.
Patch panel	Terminates structured cabling.	Cable management in wiring closet.
PoE injector/switch	Sends power over Ethernet to supported devices.	APs, IP phones, cameras without local power.
NAS	Network file storage.	Shared files/backups/media on LAN.
Repeater/extender	Extends signal coverage.	Dead zones; may reduce performance depending on design.

Notes and examples

IPv4 Address Types

Address/range	Meaning
127.0.0.1	Loopback; tests local TCP/IP stack.
169.254.x.x	APIPA/link-local; DHCP address was not obtained.
10.x.x.x	Private IPv4 range.
172.16.x.x to 172.31.x.x	Private IPv4 range.
192.168.x.x	Private IPv4 range; common SOHO LANs.
Default gateway	Router IP used to reach other networks.
Subnet mask	Defines local network portion of IP address.
DNS server	Resolves names to IP addresses.
DHCP server	Automatically assigns IP configuration.

\[ \text{Usable IPv4 hosts per typical subnet} = 2^{\text{host bits}} - 2 \]

CIDR	Mask	Typical usable hosts
/30	255.255.255.252	2
/29	255.255.255.248	6
/28	255.255.255.240	14
/27	255.255.255.224	30
/26	255.255.255.192	62
/25	255.255.255.128	126
/24	255.255.255.0	254
/16	255.255.0.0	65,534
/8	255.0.0.0	16,777,214

Common Ports and Protocols

Port	Protocol/service	Secure?	Exam cue
20/21	FTP	No	Legacy file transfer; control/data channels.
22	SSH / SFTP	Yes	Secure remote shell; SFTP uses SSH.
23	Telnet	No	Legacy remote shell; avoid when security matters.
25	SMTP	Usually no by default	Mail transfer between servers.
53	DNS	Varies	Name resolution; UDP common, TCP also used.
67/68	DHCP	No	Automatic IP configuration.
69	TFTP	No	Simple file transfer, network boot/configs.
80	HTTP	No	Web traffic without TLS.
110	POP3	No	Downloads mail from mailbox.
123	NTP	No/varies	Time synchronization.
143	IMAP	No	Mail access with server-side folders.
161/162	SNMP	Varies	Network monitoring and traps.
389	LDAP	No by default	Directory queries.
443	HTTPS	Yes	Web traffic over TLS.
445	SMB/CIFS	Varies	Windows file/printer sharing.
465/587	SMTPS/submission	Yes/STARTTLS commonly	Authenticated mail submission.
636	LDAPS	Yes	LDAP over TLS.
993	IMAPS	Yes	Secure IMAP.
995	POP3S	Yes	Secure POP3.
3389	RDP	Encrypted but protect carefully	Remote Desktop.

Wireless Standards and Selection

Standard/concept	Practical reference
802.11a	5 GHz; older.
802.11b/g	2.4 GHz; older; more interference.
802.11n	2.4 GHz and/or 5 GHz; MIMO introduced broadly.
802.11ac	5 GHz; common Wi-Fi 5.
802.11ax	Wi-Fi 6/6E family; efficiency improvements; may use 2.4, 5, and 6 GHz depending on device/AP support.
2.4 GHz	Better range/wall penetration; more congestion; fewer non-overlapping channels.
5 GHz	Higher throughput, less crowded, shorter range.
6 GHz	Cleaner spectrum where supported; shorter range; requires compatible clients/APs.
WPA2	Common secure Wi-Fi option when configured with AES.
WPA3	Newer security improvements where supported.
Enterprise mode	Uses 802.1X/RADIUS credentials.
Personal mode	Uses pre-shared key/passphrase.
WPS	Convenience pairing; often disabled for security.
Captive portal	Web-based login page, common in guest/public networks.

SOHO Router / AP Setup Checklist

Connect modem/ONT to router WAN/Internet port.
Configure LAN IP range and DHCP scope.
Set SSID, security mode, and strong passphrase.
Prefer WPA3 where all clients support it; otherwise use strong WPA2 configuration.
Disable WPS unless specifically required.
Change default administrator credentials.
Update firmware from trusted vendor source.
Configure guest network isolation if guests need Internet only.
Use port forwarding only when required; document every rule.
Place AP centrally and away from interference.
Back up configuration after successful setup.

Cabling and Termination

Cable/connector	Use	Notes
Cat 5e	Ethernet LAN.	Common for gigabit-class LANs.
Cat 6 / 6a	Ethernet LAN with better performance/headroom.	Better for newer structured cabling.
UTP	Unshielded twisted pair.	Common office/home Ethernet.
STP	Shielded twisted pair.	Helps in high-interference environments; grounding matters.
Plenum cable	Air-handling spaces.	Required by building design/code contexts; know the term.
Coaxial / F-type	Cable Internet/TV.	Screws onto cable modem/TV equipment.
Fiber	Long-distance/high-speed links.	Uses light; not affected by EMI.
LC/SC/ST	Fiber connectors.	Recognize connector types by scenario/image.
Straight-through	Standard Ethernet patching.	Common device-to-switch connections.
Crossover	Connects similar older Ethernet devices.	Auto-MDI-X reduces need on modern devices.
Rollover/console	Device management console.	Used for network device console access.
T568A/T568B	Wiring pinout standards.	Use one consistently; crossover uses different ends.

Network Command Triage

Use commands to isolate where connectivity fails: local stack, NIC, gateway, DNS, or remote route.

ipconfig /all
ping 127.0.0.1
ping <own-ip-address>
ping <default-gateway>
ping <known-good-ip>
nslookup <fqdn>
tracert <fqdn>

Result	Likely meaning
Cannot ping 127.0.0.1	Local TCP/IP stack or host firewall issue.
Cannot ping own IP	NIC/IP configuration problem.
Cannot ping gateway	Local LAN, Wi-Fi, cable, VLAN, or gateway issue.
Can ping IP but not name	DNS problem.
Trace stops after gateway	Upstream routing/ISP/firewall issue possible.
IP is 169.254.x.x	DHCP failure or unreachable DHCP server.

Common Ports and Protocols

Port	Protocol / Service	Quick Memory Cue
20/21	FTP	File transfer
22	SSH	Secure remote shell
23	Telnet	Insecure remote shell
25	SMTP	Send mail
53	DNS	Name resolution
67/68	DHCP	Automatic IP addressing
80	HTTP	Web traffic
110	POP3	Receive mail, download-oriented
143	IMAP	Receive mail, sync-oriented
161/162	SNMP	Network management
389	LDAP	Directory services
443	HTTPS	Secure web traffic
445	SMB/CIFS	Windows file sharing
3389	RDP	Remote Desktop

Common trap: SMTP sends, while POP3/IMAP receive. If the user can receive but not send mail, look at SMTP settings, authentication, firewall, or provider restrictions.

TCP vs UDP

Protocol	General Behavior	Examples
TCP	Connection-oriented, reliable delivery	HTTP/S, FTP, SSH, SMTP, IMAP, RDP
UDP	Connectionless, lower overhead	DNS queries, DHCP, streaming, VoIP, some VPN traffic

Decision rule: if reliability and ordered delivery are central, TCP is usually involved. If speed, broadcast/discovery, or real-time tolerance is central, UDP may be involved.

Network Devices

Device	Function
Modem	Connects to ISP access network
Router	Routes between networks
Switch	Connects devices within a LAN
Wireless access point	Provides Wi-Fi access to wired LAN
Firewall	Filters traffic based on rules
Patch panel	Cable termination/organization
PoE switch/injector	Provides power over Ethernet
NAS	Shared network storage
VoIP phone	Voice over IP endpoint
Load balancer	Distributes traffic across servers
Proxy	Intermediary for client requests

SOHO Router Review

Know these configuration areas:

SSID and wireless security
Admin password change
Firmware updates
DHCP scope
DNS settings
Port forwarding
Guest network
MAC filtering
Firewall rules
QoS
Static reservations
Channel selection
2.4 GHz vs 5 GHz vs 6 GHz behavior

Common trap: hiding the SSID is not strong security. Use modern encryption and strong credentials.

Wi-Fi Frequency Bands

Band	Strengths	Limitations
2.4 GHz	Longer range, better wall penetration	More interference, fewer non-overlapping channels
5 GHz	Faster, less crowded than 2.4 GHz	Shorter range
6 GHz	More spectrum, high performance	Shorter range, newer device support required

Wireless Standards Quick View

Standard	Common Band	Relative Idea
802.11a	5 GHz	Older
802.11b	2.4 GHz	Older, slow
802.11g	2.4 GHz	Older
802.11n	2.4/5 GHz	Wi-Fi 4 generation
802.11ac	5 GHz	Wi-Fi 5 generation
802.11ax	2.4/5/6 GHz depending on implementation	Wi-Fi 6 / 6E generation
802.11be	2.4/5/6 GHz depending on implementation	Wi-Fi 7 generation

Wireless Troubleshooting

Symptom	Check
Weak signal	Distance, obstacles, antenna, AP placement
Slow Wi-Fi	Interference, band, channel, client capability
Drops near microwave/Bluetooth	2.4 GHz interference
Can connect but no internet	Gateway, DNS, DHCP, ISP
Only old devices fail	Security mode, band support, standard compatibility
Roaming problems	AP placement, signal overlap, client behavior

Network Tools

Tool	Use
Cable tester	Checks cable continuity/wiring
Loopback plug	Tests port transmit/receive
Toner probe	Traces cable paths
Crimper	Attaches connectors
Punchdown tool	Terminates wires to patch panels/keystone jacks
Wi-Fi analyzer	Reviews channels, signal, interference
Multimeter	Tests voltage/continuity
Network tap	Captures traffic passively
Time-domain reflectometer	Locates cable faults/distance to fault

Connectivity Scenario Table

Scenario	Most Likely Direction
One wired device offline	Cable, port, NIC, IP config
Multiple wired devices on same switch offline	Switch, uplink, VLAN, power
One wireless device offline	Wi-Fi settings, saved profile, adapter, signal
All wireless devices offline	AP/router, internet, DHCP, power
User has IP but no DNS	DNS setting or DNS server
User has APIPA	DHCP not reachable
Intermittent connectivity	Cable damage, interference, failing hardware, IP conflict
Slow internet for everyone	ISP, router, bandwidth saturation, DNS
Slow access to one site	Site, routing, DNS, remote service

Network Layer Thinking

Use this simplified path when a device cannot reach a resource:

Physical/link: cable, Wi-Fi signal, link lights.
IP configuration: IP address, subnet mask, gateway, DNS.
Local reachability: ping loopback, own IP, gateway.
Remote reachability: ping external IP.
Name resolution: test DNS.
Application/service: port, firewall, credentials, server.

Printers and Imaging

Printer Type Selection

Printer type	Choose when	Consumables	Common issues
Laser	High-volume text, office use, fast output.	Toner, drum, fuser, transfer components.	Streaks, ghosting, jams, fuser issues.
Inkjet	Photo/color use, lower device cost.	Ink cartridges, printhead.	Clogged nozzles, streaks, wet/smeared output.
Thermal	Receipts, labels, low-maintenance point-of-sale.	Thermal paper or ribbon depending type.	Faded output, wrong paper, heat sensitivity.
Impact	Multipart forms, harsh/legacy environments.	Ribbon, tractor-feed paper.	Noisy, printhead/ribbon issues.
Virtual printer	Print to PDF/XPS or redirect output.	None physical.	Driver/default printer/output path confusion.

Notes and examples

Laser Printing Process

Step	What happens	Related symptom
Processing	Printer receives and prepares job.	Job stuck, wrong driver, memory issue.
Charging	Drum receives uniform charge.	Background shading or uneven image.
Exposing	Laser writes image to drum.	Missing/incorrect image.
Developing	Toner adheres to charged image.	Faded print, toner distribution issue.
Transferring	Toner moves to paper.	Repeating defects, transfer roller issues.
Fusing	Heat/pressure bonds toner to paper.	Smearing if toner is not fused.
Cleaning	Residual toner removed.	Ghosting or repeated marks.

Printer Troubleshooting Matrix

Symptom	Likely cause	Best checks
Paper jam	Worn rollers, wrong paper, debris, tray alignment.	Remove jam fully, inspect path, verify media type.
Faded laser output	Low toner, bad toner cartridge, density setting.	Shake/replace toner, check settings.
Toner smears	Fuser problem or wrong media.	Check fuser, media type, printer temperature readiness.
Ghost images	Drum/fuser/cleaning issue.	Replace affected consumable.
Inkjet streaks	Clogged nozzle, low ink, dirty printhead.	Run cleaning/calibration; replace cartridge if needed.
Thermal blank output	Paper loaded backward, wrong paper, failed printhead.	Verify thermal paper orientation.
Impact faint output	Worn ribbon or printhead.	Replace ribbon; inspect printhead.
Incorrect printer output	Wrong driver, wrong default printer, bad application setting.	Verify driver and print queue.
Network printer offline	IP change, Wi-Fi issue, print spooler, firewall.	Ping printer, check IP/reservation, restart spooler/device.

Printers

Printers are heavily scenario-driven. Know the print technology, the imaging process, and which consumable causes which symptom.

Printer Types

Printer Type	Strengths	Common Issues
Laser	Fast text, office use	Toner, drum, fuser, transfer roller, paper path
Inkjet	Photos, color, low initial cost	Ink cartridges, clogged nozzles, alignment
Thermal	Receipts, labels	Thermal paper, print head
Impact	Multipart forms	Ribbon, tractor feed, print head

Laser Printing Process

Step	Purpose
Processing	Printer receives and prepares job
Charging	Drum receives electrical charge
Exposing	Laser writes image to drum
Developing	Toner attaches to image areas
Transferring	Toner moves from drum to paper
Fusing	Heat/pressure bond toner to paper
Cleaning	Excess toner removed

Printer Symptom Table

Symptom	Likely Cause
Streaks or lines	Dirty rollers, toner/drum issue, inkjet clogged nozzle
Faded print	Low toner/ink, economy mode, transfer issue
Ghosting	Fuser or drum problem
Paper jams	Rollers, paper type, tray alignment, debris
Creased paper	Rollers, paper path, fuser
Blank pages	Empty toner/ink, transfer issue, wrong driver, sealed cartridge
Speckling	Toner spill, drum, cleaning issue
Incorrect colors	Calibration, cartridge, color profile, driver

Common trap: for laser printers, repeated image defects often point to a rotating component such as the drum or fuser.

Virtualization and Cloud

Virtualization Concepts

Concept	What it means	Exam cue
Hypervisor	Software/firmware that runs virtual machines.	Required to host VMs.
Type 1 hypervisor	Runs directly on hardware.	Server/datacenter virtualization.
Type 2 hypervisor	Runs on top of a host OS.	Desktop lab/testing VM.
Guest OS	OS inside a VM.	Needs virtual hardware and drivers/tools.
Virtual switch	Connects VMs to virtual/physical networks.	VM network design.
Snapshot/checkpoint	Captures VM state for rollback.	Short-term change safety, not backup.
Clone/template	Creates repeatable VM copies.	Rapid deployment/testing.
Resource allocation	CPU, RAM, storage assigned to VM.	Over-allocation causes performance issues.
Sandboxing	Isolated environment for testing.	Reduce risk to production host/network.

Notes and examples

VM Network Modes

Mode	VM can access	Other devices can access VM?	Use when
NAT	External networks through host translation.	Usually not directly.	Simple Internet access for lab VM.
Bridged	Same LAN as host.	Yes, like a physical device.	VM must be reachable on LAN.
Host-only	Host and isolated VMs.	No external LAN by default.	Isolated testing.
Internal/private	Only VMs on same virtual network.	No host or LAN unless configured.	Multi-VM isolated lab.

Cloud Models and Service Selection

Model	You manage more	Provider manages more	Choose when
On-premises	Hardware through applications.	Little/none.	Full control, local constraints, existing infrastructure.
IaaS	OS, apps, data; sometimes network config.	Physical hardware and virtualization.	Need VM-like control without owning hardware.
PaaS	Application code/data/config.	OS, runtime platform, scaling components.	Developers need platform without server maintenance.
SaaS	User settings and data usage.	Application and infrastructure.	Need ready-to-use software.

Cloud characteristic	Meaning
Rapid elasticity	Resources can scale up/down quickly.
Measured service	Usage is metered/monitored.
Resource pooling	Shared provider infrastructure serves multiple customers.
On-demand self-service	Users/admins can provision without manual provider interaction.
Broad network access	Services are reachable over networks by supported clients.
High availability	Design goal to keep services accessible despite component failures.
File synchronization	Data replicated between device and cloud/service.

Virtualization Basics

Concept	Review
Virtual machine	Software-defined computer running on a host
Host	Physical system running the virtualization platform
Guest	VM operating system
Hypervisor	Software layer that runs VMs
Type 1 hypervisor	Runs directly on hardware
Type 2 hypervisor	Runs on top of a host OS
Virtual switch	Connects VMs to networks
Snapshot	Point-in-time VM state
Resource allocation	CPU, RAM, storage, and network assigned to VM

VM Resource Traps

Trap	Review
Too little RAM	Guest OS runs slowly or fails
Too little storage	Install/update failures
No virtualization support enabled	VM performance/features may fail
Network mode confusion	NAT, bridged, and host-only behave differently
Snapshot as backup	Snapshots are not a full backup strategy
Overcommitting resources	Host and guests all suffer performance issues

VM Network Modes

Mode	Behavior
NAT	VM shares host network access behind translation
Bridged	VM appears as a peer on the physical network
Host-only	VM communicates with host/private virtual network only
Internal/private	VM communicates with selected VMs only

Troubleshooting Methodology

CompTIA identifies the methodology as useful workplace practice, not a tested 220-1201 objective. For practice questions, use the symptoms, tests, and constraints actually provided. Official objectives .

Workplace Troubleshooting Flow

Step	What to do	Support practice
1. Identify the problem	Gather information, question user, identify changes, duplicate issue if possible.	Do not jump to replacement before facts.
2. Establish a theory	Start with obvious/common causes.	Loose cable, power, wrong input, Wi-Fi disabled, low toner.
3. Test the theory	Confirm or revise theory.	If theory fails, establish a new one.
4. Establish a plan and implement	Plan fix, consider impact, apply solution.	Avoid risky changes without backup/approval context.
5. Verify full functionality	Confirm issue resolved and preventive measures applied.	Test with user workflow, not just component power-on.
6. Document findings	Record symptoms, cause, fix, and follow-up.	Documentation is a valid final step.

Notes and examples

Hardware Symptom Matrix

Symptom	Likely cause	Quick isolation
No power	PSU, outlet, cable, switch, motherboard short.	Test outlet/cable, check PSU switch, minimal boot.
Fans spin, no POST	RAM, CPU power, motherboard, GPU, firmware.	Reseat RAM/GPU, check CPU power, beep/LED codes.
Random shutdown	Overheating, PSU, failing board, battery.	Check temperatures, fans, dust, PSU load.
Burning smell	Electrical failure, overheated component.	Power off immediately; inspect safely.
Clicking drive	Mechanical HDD failure.	Stop unnecessary use; back up/recover if possible.
Slow storage	HDD fragmentation, failing disk, full disk, background tasks.	Check SMART/health, free space, disk activity.
BSOD/kernel panic	Driver, RAM, storage, overheating, OS issue.	Note error, check recent changes, diagnostics.
Date/time resets	CMOS battery.	Replace battery and reset firmware settings.
System beeps	POST hardware fault.	Interpret vendor beep/LED codes.

Network Symptom Matrix

Symptom	Likely cause	First checks
No link light	Cable, port, NIC, switch power.	Reseat cable, test known-good cable/port.
Connected, no Internet	Gateway, DNS, upstream ISP, captive portal.	Check IP/gateway/DNS; ping gateway then known IP.
APIPA address	DHCP unreachable.	Check DHCP server/router, VLAN, Wi-Fi association.
Can access IP not names	DNS issue.	Check DNS server configuration and resolution.
Slow Wi-Fi	Distance, interference, congestion, band selection.	Move closer, change band/channel, reduce interference.
Intermittent connection	Cable damage, weak Wi-Fi, duplex/speed mismatch, power saving.	Test wired path, replace cable, check logs/settings.
One device affected	Client configuration/NIC/driver.	Compare with working device on same network.
All devices affected	Router/switch/AP/ISP/power.	Check infrastructure and upstream connection.

Safety and Handling

Situation	Safe practice
Inside PC	Power down, unplug when appropriate, use ESD precautions.
ESD-sensitive parts	Use antistatic strap/mat or proper grounding.
Power supplies	Do not open PSU; capacitors can retain charge.
Laser printer	Let fuser cool; toner is fine particulate.
Batteries	Do not puncture/swollen batteries; recycle properly.
CRT/legacy high voltage	Avoid internal service unless trained.
Liquids	Power off, disconnect, dry/inspect before reapplying power.
Lifting equipment	Use proper lifting technique or assistance.

Field Tools

Tool	Use
Phillips/flathead/Torx drivers	Open cases, replace components.
ESD strap/mat	Protect components from electrostatic discharge.
Multimeter	Test voltage, continuity, basic electrical faults.
PSU tester	Quick PSU output check.
Cable tester	Validate Ethernet cable wiring/continuity.
Loopback plug	Test port transmit/receive function.
Toner probe	Trace cable runs.
Punchdown tool	Terminate wires on patch panels/keystone jacks.
Crimper	Attach modular connectors.
Wi-Fi analyzer	Check signal strength, channel congestion.
Compressed air	Remove dust; hold fans to prevent overspinning.
Thermal paste	Reinstall CPU heat sink properly.
Known-good cable/device	Fast isolation by substitution.

Final Review Checklist

Before moving on, make sure you can answer these quickly:

What symptom points to DHCP failure?
Which service resolves names to IP addresses?
Which ports are used by DNS, DHCP, HTTPS, SMB, SSH, and RDP?
Why is RAID not a backup?
When would you choose bridged instead of NAT networking for a VM?
What is the order of the laser printing process?
Which Wi-Fi band has better range, and which typically offers higher throughput?
What is the difference between M.2, SATA, and NVMe?
Which printer type is best for multipart forms?
What should you do before replacing hardware in a troubleshooting scenario?

Notes and examples

Final Readiness Checklist

Before sitting for CompTIA A+ Core 1 (220-1201), make sure you can:

Identify common ports, protocols, and network services from scenarios.
Troubleshoot DHCP, DNS, gateway, Wi-Fi, and cabling problems.
Distinguish routers, switches, access points, modems, firewalls, and NAS devices.
Match storage, RAM, CPU, motherboard, and power components for compatibility.
Diagnose printer issues by printer type and symptom.
Recognize laptop and mobile device replacement/connection scenarios.
Explain basic virtualization and cloud service models.
Apply a structured troubleshooting process without skipping verification.
Choose the safest and most practical “first” or “best” action.

For the next step, use original practice questions in a question bank with focused topic drills and detailed explanations so you can convert this Cheat Sheet into exam-ready decision-making.

CompTIA A+ Core 1 Cheat Sheet

Apply these distinctions in the current Core 1 practice bank . Review the supplied test results and constraints before reading the choices; selected app questions include diagrams that can be enlarged.

This Cheat Sheet is an IT Mastery study companion for candidates preparing for CompTIA A+ Core 1 (220-1201). Use it to refresh the most testable ideas before moving into topic drills, mock exams, and original practice questions with detailed explanations.

Build practical recognition: identify the device, interpret the symptom and test results, and choose the action or technology that meets the support requirements.

High-Yield Core 1 Topic Map

Area	What to Know Fast	Common Exam Angle
Mobile devices	Laptop parts, displays, batteries, docking, wireless, mobile accessories	Replace/upgrade the correct component
Networking	Ports, protocols, IPv4/IPv6, wireless, cabling, SOHO devices	Identify service, symptom, or configuration issue
Hardware	Motherboards, CPUs, RAM, storage, power, printers, displays	Select compatible hardware or diagnose failure
Virtualization/cloud	VM resources, hypervisors, cloud models, cloud characteristics	Match service model or deployment need
Troubleshooting	Methodical diagnosis, hardware symptoms, network symptoms	Choose the best next step

Core Troubleshooting Method

The formal troubleshooting methodology is useful workplace practice; CompTIA explicitly excludes that methodology itself from the tested 220-1201 objectives. Use this flow to organize a diagnosis, while choosing exam answers from the technical evidence. See the current objectives .

    flowchart TD
	A[Identify the problem] --> B[Establish a theory]
	B --> C[Test the theory]
	C -->|Theory confirmed| D[Plan and implement the fix]
	C -->|Theory not confirmed| B
	D --> E[Verify full functionality]
	E --> F[Document findings and actions]

Common Troubleshooting Traps

Trap	Better Exam Behavior
Replacing hardware before testing	Confirm the likely cause first
Ignoring user changes	Ask what changed recently
Skipping simple checks	Verify power, cables, links, and settings
Choosing the most technical option	Choose the most appropriate support step
Fixing one symptom only	Verify full functionality afterward
Forgetting documentation	Document after resolution

Power and Cooling

Power Supply Concepts

Concept	What It Means
Wattage	Total power capacity
Efficiency rating	How efficiently AC is converted to DC
Modular PSU	Detachable cables reduce clutter
24-pin motherboard connector	Main board power
CPU power connector	Dedicated CPU power
PCIe power	Extra power for graphics cards
SATA power	Storage drives and some accessories

Notes and examples

Power Troubleshooting Clues

Symptom	Likely Area
No power, no fans, no lights	Outlet, power cable, PSU switch, PSU
Powers on then shuts off	Overheating, short, PSU, CPU cooling
Random shutdowns under load	PSU capacity, heat, failing component
Burning smell	Stop and inspect; do not keep powering on
New GPU causes instability	Insufficient PSU wattage or missing PCIe power

Cooling Review

Cooling Item	Purpose
Heat sink	Transfers heat away from CPU/GPU
Thermal paste	Improves contact between chip and heat sink
Fan	Moves air over heat sink or through case
Liquid cooling	Uses pump/radiator loop
Airflow direction	Front/bottom intake, rear/top exhaust is common
Dust removal	Restores cooling efficiency

Common trap: adding more fans does not help if airflow is blocked, the heat sink is loose, or thermal paste is missing.

Displays, Video, and Connectors

Connector	Common Use	Notes
HDMI	TVs, monitors, projectors	Carries audio and video
DisplayPort	Monitors, docking, high refresh	Common on business systems
USB-C	Data, power, display, docking	Capabilities vary by device and cable
Thunderbolt	High-speed data/display/docking	Uses USB-C connector in newer versions
VGA	Legacy analog video	No audio, lower quality
DVI	Older digital/analog display	Legacy desktop displays

Display Symptoms

Symptom	Check First
No display	Power, input source, cable, brightness, external/internal toggle
Dim laptop screen	Brightness, backlight, inverter on older systems
Flickering	Cable, refresh rate, GPU driver, panel issue
Artifacts	GPU, overheating, cable, display panel
External display works but internal does not	Laptop screen, cable, backlight, display settings

Mobile Devices

Laptop Hardware

Component	Review Point
Battery	Swollen or failing batteries require careful replacement
Keyboard/touchpad	Often replaceable as assemblies
Display panel	Match size, connector, resolution, mounting
Wi-Fi/Bluetooth card	May use M.2 or proprietary form factor
Storage	M.2 NVMe, SATA M.2, or 2.5-inch SATA depending on model
Memory	Often SO-DIMM, but some systems have soldered RAM
Webcam/microphone	Privacy settings and drivers can mimic hardware failure
Docking station	Can provide power, display, USB, Ethernet, audio

Notes and examples

Mobile Accessories

Accessory	Exam-Relevant Idea
Port replicator/dock	Expands connectivity
Touch pen/stylus	Digitizer support may be required
Screen protector	Physical protection
Privacy filter	Limits viewing angle
External keyboard/mouse	Bluetooth or USB
Hotspot	Shares cellular data over Wi-Fi
Headset	Audio input/output support
NFC devices	Short-range tap-based communication

Mobile Device Connectivity

Technology	Use Case
Wi-Fi	Local wireless networking
Bluetooth	Short-range peripherals
NFC	Tap-to-pair or tap-to-pay style interactions
Cellular	Mobile WAN access
GPS	Location services
USB tethering	Share mobile data over USB
Mobile hotspot	Share cellular data over Wi-Fi

Mobile Troubleshooting Clues

Symptom	First Checks
Battery drains quickly	Screen brightness, background apps, weak signal, battery health
Device will not charge	Cable, charger, port debris, battery, charging settings
Overheating	Apps, environment, battery, blocked ventilation
No wireless	Airplane mode, Wi-Fi toggle, saved network, signal
No Bluetooth pairing	Discoverability, distance, previous pairing, battery
Touchscreen unresponsive	Restart, clean screen, case/screen protector, digitizer
App crashes	Update app/OS, clear cache, storage space, reinstall

IP Addressing Review

IPv4 Basics

Concept	Review
IPv4 address	32-bit address, commonly dotted decimal
Subnet mask	Separates network and host portions
Default gateway	Router used to reach other networks
DNS server	Resolves names to IP addresses
DHCP	Automatically assigns IP settings
Static IP	Manually assigned configuration
APIPA	Self-assigned address when DHCP fails, commonly 169.254.x.x

Notes and examples

IPv4 Private Address Ranges

Range	Common Use
10.x.x.x	Private networks
172.16.x.x through 172.31.x.x	Private networks
192.168.x.x	Home and small office networks

IPv6 Basics

Concept	Review
IPv6 address	128-bit address written in hexadecimal groups
Link-local	Local network segment communication
Global unicast	Publicly routable IPv6 address
Loopback	::1
SLAAC	IPv6 automatic address configuration method

Quick IP Symptom Rules

Symptom	Likely Issue
169.254.x.x address	DHCP failure
Can ping IP but not name	DNS issue
Can reach LAN but not internet	Gateway, routing, ISP, firewall
One device offline	Local device config, cable, Wi-Fi, NIC
All devices offline	Router, modem, ISP, switch, power
Duplicate IP warning	Static conflict or DHCP issue

Cabling and Connectors

Cable / Connector	Use
RJ45	Ethernet twisted pair
RJ11	Telephone/DSL-style connections
F-type	Coaxial cable, cable internet/TV
LC/SC/ST	Fiber connectors
USB-A	Common legacy USB host port
USB-C	Reversible connector for data/power/display
Lightning	Apple mobile accessory connector on many older devices
SATA	Internal storage data connection
Molex	Legacy internal power connector
IEC power cable	Common desktop/monitor power cable

Notes and examples

Copper Ethernet

Term	Review
Cat 5e	Common gigabit-capable cabling
Cat 6	Higher performance than Cat 5e
Cat 6a	Better for higher-speed/longer supported runs
Plenum	Fire-rated jacket for air-handling spaces
Shielded twisted pair	Helps reduce interference
Unshielded twisted pair	Common general Ethernet cabling

Fiber Review

Fiber Type	Review
Single-mode	Longer distances, laser light
Multimode	Shorter distances, common inside buildings
Fiber advantage	Long distance, high bandwidth, EMI resistance
Fiber caution	Fragile, requires correct optics/connectors

Command-Line Network Tools

Command	Use
ipconfig / ifconfig / ip	View IP configuration
ping	Test basic reachability
tracert / traceroute	Show route path
nslookup / dig	Test DNS resolution
netstat	View connections/listening ports
arp	View IP-to-MAC mappings
route	View or modify routing table
hostname	Display system name
net use	Map/use Windows network resources

Command Decision Rules

Scenario	Best First Command
“What IP address did DHCP assign?”	ipconfig / ifconfig / ip
“Can this host reach the gateway?”	ping
“Where does the path fail?”	tracert / traceroute
“Is DNS resolving this hostname?”	nslookup / dig
“What connections are open?”	netstat
“Is the MAC address cached?”	arp

Cloud Computing

Cloud Service Models

Model	Provider Manages More?	Candidate Must Recognize
IaaS	Less	Virtual machines, storage, networks
PaaS	Medium	App platform/runtime without managing servers directly
SaaS	More	Complete application delivered over network

Notes and examples

Decision rule: if the customer manages the OS, think IaaS. If the customer deploys code to a managed platform, think PaaS. If the customer simply uses the application, think SaaS.

Cloud Deployment Models

Model	Meaning
Public cloud	Shared provider infrastructure
Private cloud	Cloud-like environment dedicated to one organization
Hybrid cloud	Mix of private and public resources
Community cloud	Shared by organizations with common needs

Cloud Characteristics

Characteristic	Review
Rapid elasticity	Scale resources up/down quickly
Metered utilization	Pay/measure by usage
High availability	Designed to reduce downtime
File synchronization	Keep files consistent across devices
Shared resources	Multi-tenant/provider infrastructure
Virtual desktop	Desktop environment delivered remotely

Common trap: cloud does not automatically mean “more secure,” “always cheaper,” or “no administration.” The correct answer depends on requirements.

Security-Relevant Core 1 Concepts

Although Core 1 is hardware/network focused, some questions include basic security context.

Concept	Why It Matters
WPA2/WPA3	Wireless encryption/security modes
Guest network	Separates visitors from internal resources
Default admin password	Must be changed on SOHO devices
Firmware updates	Fix bugs and security issues
Evil twin/rogue AP	Wireless impersonation risk
Physical privacy filter	Prevents shoulder surfing
Cable locks	Physical device theft deterrent
NFC/Bluetooth controls	Reduce unwanted pairing or data exposure
Secure disposal	Storage devices may contain sensitive data

Common trap: do not choose convenience over basic protection when the question asks for the best secure configuration.

High-Yield “Best Answer” Decision Rules

Question Wording	What to Do
“First”	Choose the earliest safe diagnostic step
“Best”	Choose the most complete and appropriate answer
“Most likely”	Match the strongest symptom clue
“Least expensive”	Avoid unnecessary replacement
“Secure”	Prefer stronger encryption/authentication/configuration
“Small office/home office”	Think practical router, Wi-Fi, DHCP, NAT, basic firewall
“Intermittent”	Consider heat, loose cables, interference, failing components
“After upgrade/change”	Focus on the recent change
“All users affected”	Look upstream or shared infrastructure
“One user affected”	Look at local device/configuration

Common Candidate Mistakes

Memorization Without Scenario Practice

Knowing that DNS uses port 53 is useful. But the exam may describe a user who can reach 8.8.8.8 but cannot open websites by name. That is a DNS scenario, not a generic “internet down” scenario.

Confusing Similar Technologies

Confused Pair	Difference
Router vs switch	Router connects networks; switch connects devices within a network
Modem vs router	Modem connects ISP medium; router routes/NATs between networks
Access point vs router	AP provides wireless access; router routes traffic
DNS vs DHCP	DNS resolves names; DHCP assigns IP settings
POP3 vs IMAP	POP3 downloads mail; IMAP syncs mail
SATA SSD vs NVMe SSD	Both can be SSDs; interface/protocol differs
USB-C vs Thunderbolt	Same connector may not mean same capabilities
Type 1 vs Type 2 hypervisor	Bare-metal vs hosted
SaaS vs PaaS	Complete app vs managed app platform
RAID 0 vs RAID 1	Striping speed vs mirroring redundancy

Notes and examples

Overlooking Compatibility

Core 1 frequently tests whether a part actually fits or works:

RAM generation and form factor
CPU socket and chipset
PSU wattage and connectors
M.2 keying and NVMe/SATA support
Laptop display connector and size
Docking station power/display support
Wi-Fi standard and band support
Printer driver and operating system compatibility

Rapid Review Tables

“What Failed?” Symptom Anchors

Clue	Think
Clicking drive	HDD failure
169.254 address	DHCP failure
Can ping IP, not name	DNS failure
Ghost images on laser print	Drum/fuser area
Laptop shuts off under load	Heat or power
New RAM causes no boot	RAM compatibility/seating
Wi-Fi weak far from router	Range/interference
Only send mail fails	SMTP
No boot device	Drive detection or boot order
Random reboots after GPU upgrade	PSU or heat
VM cannot access LAN like a normal host	Network mode may be NAT/host-only

Notes and examples

“Which Tool?” Anchors

Need	Tool
Trace cable in wall	Toner probe
Verify Ethernet pinout	Cable tester
Terminate patch panel	Punchdown tool
Attach RJ45 connector	Crimper
Check voltage	Multimeter
Analyze Wi-Fi channels	Wi-Fi analyzer
Test NIC port	Loopback plug
Capture traffic	Network tap

“Which Network Service?” Anchors

Need	Service
Assign IP addresses automatically	DHCP
Resolve names to IP addresses	DNS
Secure remote command-line access	SSH
Insecure legacy remote command line	Telnet
Secure web access	HTTPS
Windows file/printer sharing	SMB
Remote Windows GUI session	RDP
Send email	SMTP
Sync mailbox folders	IMAP

Practice Plan After This Cheat Sheet

Use this page as a checklist, then move into IT Mastery practice:

Start with topic drills for ports, protocols, hardware, printers, mobile devices, and networking.
Review detailed explanations for every missed question, including why the wrong options are wrong.
Mix topics after drilling. The real exam can combine hardware, networking, and troubleshooting in one scenario.
Take mock exams only after targeted drilling. Use mock results to find weak areas, not just to predict readiness.
Redo missed questions later. Repetition after a delay confirms whether you learned the concept.

Put the review into practice

Study Plan