Domain 1: Mobile Devices
- Laptop RAM uses SO-DIMM modules (DDR4 or DDR5), roughly half the length of a desktop DIMM, seated at an angle and then pressed flat to lock.
- Laptop storage is typically an M.2 NVMe SSD or 2.5 inch SATA drive; many thin ultrabooks solder storage directly to the motherboard, making it non-upgradeable.
- Bluetooth pairs nearby peripherals (headsets, keyboards, mice) over short range, NFC enables contactless payment and one-tap pairing, and GPS provides location services.
- Cellular data (LTE or 5G) gives a mobile device wide-area internet access; a mobile hotspot shares that connection with other devices over Wi-Fi, USB, or Bluetooth tethering.
- USB-C is the standard reversible charging and data port on current laptops and phones; it supports USB Power Delivery (PD) for fast charging and DisplayPort Alt Mode for external video.
- Docking stations and port replicators expand a laptop's I/O, adding extra displays, Ethernet, and USB ports through a single USB-C or Thunderbolt cable.
- Laptop displays use IPS, OLED, or older TN panel technology; a digitizer layered over the screen senses finger or stylus touch input.
- Laptop batteries are lithium-ion; avoid deep discharges and heat exposure to prolong lifespan, and replace a swollen battery immediately rather than continuing to use it.
- Mobile device synchronization keeps contacts, email, photos, and app data consistent across devices through a cloud account or a direct wired connection.
- Airplane mode disables all radios at once (cellular, Wi-Fi, Bluetooth, GPS); Wi-Fi and Bluetooth can typically be re-enabled independently afterward.
- Field-replaceable laptop components commonly include the battery, RAM, storage, and keyboard, though many modern ultrabooks solder RAM and storage to the board.
Domain 2: Networking
- RJ45 (8P8C) connectors terminate twisted-pair Ethernet; Cat5e supports 1 Gbps and Cat6 supports 10GBASE-T over short runs, with a 100 meter (328 ft) maximum run length for copper.
- RFC 1918 private address ranges are 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16; NAT/PAT lets many private hosts share a single public IP.
- 169.254.0.0/16 is APIPA (link-local), self-assigned when no DHCP server responds and never routed; 127.0.0.0/8 is the loopback range and never appears on the wire.
- DHCP uses the DORA exchange (Discover, Offer, Request, Acknowledge) over UDP ports 67 (server) and 68 (client) to hand out an IP, subnet mask, gateway, DNS, and lease time.
- Key well-known ports to memorize: HTTP 80, HTTPS 443, SSH 22, Telnet 23, FTP 20/21, SMTP 25, DNS 53, DHCP 67/68, and SMB 445.
- In the crowded 2.4 GHz Wi-Fi band, use only the non-overlapping channels 1, 6, and 11 to avoid co-channel interference between neighboring access points.
- ping sends ICMP echo requests to test reachability and latency, and tracert/traceroute maps each hop along the path to a destination.
- auto-MDIX lets modern switch ports automatically detect and swap transmit/receive pairs, so crossover cables are no longer needed between like devices.
- Managed switches add VLANs, QoS, SNMP monitoring, and port mirroring for traffic segmentation and visibility; unmanaged switches offer none of that.
- Routers operate at OSI Layer 3 and forward packets between IP networks by routing table lookup; switches operate at Layer 2 and forward frames by MAC address.
- Fiber optic cabling (single-mode for long haul, multimode for shorter runs) is immune to electromagnetic interference and supports much longer distances than copper.
Domain 3: Hardware
- SSDs use NAND flash with no moving parts for sub-millisecond access and shock resistance; NVMe SSDs run over PCIe lanes and far exceed SATA's roughly 550 MB/s ceiling.
- M.2 slots are keyed B (SATA only), M (PCIe NVMe), or B+M; an NVMe M-key drive will not fit or function in a SATA-only B-key slot.
- DDR5 and DDR4 desktop DIMMs are not interchangeable with each other or with prior generations; the notch position and pin count differ so an incompatible module physically will not seat.
- Dual-channel memory requires matched modules installed in the correct paired (often same colored) slots per the motherboard manual; the wrong slots drop the system to single-channel bandwidth.
- Power supply sizing: total the rated wattage of every component, add roughly 20-30 percent headroom, and choose an 80 PLUS-rated unit with the connectors (PCIe 6/8-pin or 12VHPWR) the GPU requires.
- The PSU converts AC mains (120V/240V) into the DC rails a PC needs (+12V, +5V, +3.3V) plus a standby rail that keeps the board powered enough to respond to the power button.
- RAID levels to know: RAID 0 stripes for speed with no redundancy, RAID 1 mirrors, RAID 5 stripes with distributed parity to survive one drive failure, and RAID 10 mirrors then stripes for both redundancy and performance.
- DisplayPort and HDMI carry digital video and audio; converting either to analog VGA requires an active, powered adapter that performs digital-to-analog conversion, not a passive pin adapter.
- Overheating and thermal throttling are commonly fixed by clearing dust from vents and fans, confirming case airflow direction, and reapplying thermal paste between the CPU/GPU and heatsink.
- Laptops with switchable or hybrid graphics use the low-power integrated GPU on battery and the discrete GPU when plugged in or under heavy load.
- exFAT removes FAT32's 4 GB file size and roughly 2 TB volume limits and is the common cross-platform choice for large removable media, while NTFS remains required for the Windows system volume.
Domain 4: Virtualization and Cloud Computing
- A hypervisor abstracts physical hardware into virtual machines; Type 1 (bare-metal) hypervisors like ESXi or Hyper-V run directly on hardware, while Type 2 hypervisors run on top of a host OS.
- Virtualization enables server consolidation and workload isolation, letting one physical host run multiple independent guest operating systems.
- Containers (for example Docker) share the host OS kernel for lightweight, fast-starting, isolated application environments, unlike VMs, which each run a full guest OS.
- Cloud service models: SaaS (provider manages the entire application, e.g. Microsoft 365), PaaS (provider manages the platform and runtime), and IaaS (the customer manages the OS and up, provider manages the hardware).
- Cloud deployment models include public (shared infrastructure), private (dedicated to one organization), hybrid (a mix of both), and community (shared among organizations with common requirements).
- Rapid elasticity lets cloud resources scale up or down automatically to match demand, and metered pay-as-you-go billing charges only for resources actually consumed.
- A VM snapshot captures a point-in-time image of a virtual machine's disk and memory state, enabling a quick rollback if a change goes wrong.
- VM resource planning covers vCPU count, allocated RAM, storage provisioning (thin or thick), and a network connection method (bridged, NAT, or host-only).
- Cloud cost control practices include right-sizing oversized instances, scheduling non-production resources to shut down outside business hours, and moving cold data to lower-cost archive storage tiers.
- High availability in the cloud is achieved by distributing workloads across multiple availability zones or regions so a single data center failure does not cause an outage.
Domain 5: Hardware and Network Troubleshooting
- The CompTIA troubleshooting methodology: identify the problem, establish a theory of probable cause, test the theory, establish a plan of action, implement the solution, verify full functionality and apply preventive measures, and document findings and outcomes.
- POST beep codes signal hardware failures (commonly bad RAM or a GPU issue) before the display initializes; consult the motherboard or BIOS vendor's beep code chart to interpret them.
- Always wear an ESD anti-static wrist strap and use proper grounding before handling internal components, since electrostatic discharge can silently damage sensitive chips.
- A negotiated link speed lower than expected (for example 100 Mbps instead of 1 Gbps) usually points to a damaged cable, a duplex mismatch, or cabling rated below the required category.
- Intermittent outages or broadcast storms on a switched network can indicate a switching loop; check cabling and port status and confirm Spanning Tree Protocol (STP) is enabled.
- Cable runs near motors, fluorescent lighting, or power lines suffer electromagnetic interference (EMI); replace them with shielded (STP) cabling routed away from the source, or use fiber, which is immune to EMI.
- Slow boot or performance issues are diagnosed by checking S.M.A.R.T. drive health and free disk space, disabling unnecessary startup programs, and confirming the memory channel mode in BIOS/UEFI.
- Sustained high CPU or GPU temperatures that cause clock speeds to drop indicate thermal throttling from inadequate cooling; a process stalled on slow I/O points to the storage subsystem instead.
- Common printer symptoms: faded or light print output points to low toner or a failing imaging drum on a laser printer, while vertical lines or streaks often indicate a dirty or scratched drum.
- No-boot troubleshooting isolates whether the fault is power (dead PSU, no fans spinning), display (no POST beep but fans spin), or storage (POST completes but the OS fails to load).
- Weak Wi-Fi signal or intermittent wireless drops are commonly resolved by relocating the access point away from interference sources, changing channels, or adding an additional AP for coverage.
CompTIA A+ Core 1 (220-1201) exam tips
- Memorize well-known port numbers and RFC 1918 private ranges cold - they are fast, easy points if you have them instantly.
- Learn the seven-step CompTIA troubleshooting methodology in exact order; scenario questions often ask which step comes next.
- Expect performance-based questions (PBQs) early in the exam; they take the most time, so consider flagging one and returning to it rather than losing time on later multiple-choice items.
- Know connector and cable types by sight (RJ45, USB-C, M.2 keying, DisplayPort/HDMI) since several questions describe or show a physical connector.
- Read for the BEST or FIRST answer when multiple options look technically valid; questions often hinge on the safest or earliest correct step, such as ESD precautions before touching hardware.
- Build hands-on familiarity with RAID levels and hypervisor types (Type 1 vs Type 2) since these concepts are tested with applied scenarios, not just definitions.
Study guide FAQ
How many exams do I need to pass, and how does Core 1 differ from Core 2?
You must pass two separate exams to earn the CompTIA A+ certification: Core 1 (220-1201) and Core 2 (220-1202). Core 1 covers mobile devices, networking, hardware, virtualization and cloud computing, and hardware and network troubleshooting. Core 2 covers operating systems, security, software troubleshooting, and operational procedures. Each exam is scored and passed independently.
What is the passing score, and how long is the exam?
CompTIA A+ Core 1 (220-1201) has a maximum of 90 questions with a 90 minute time limit, and requires a scaled score of 675 out of 900 to pass. Questions are a mix of multiple-choice and performance-based simulations (PBQs).
Are these official CompTIA questions?
No. These are independent practice questions written to reflect the topics and style of the CompTIA A+ Core 1 (220-1201) objectives. They are a study aid, not actual exam content, and are not affiliated with or endorsed by CompTIA.
Who is CompTIA A+ Core 1 designed for?
A+ targets entry-level IT support technicians such as help desk agents, desktop support staff, and field service technicians. There is no required prerequisite certification, though CompTIA recommends some hands-on exposure to PC hardware and networking before attempting the exam.
Do I need to take Core 1 and Core 2 at the same time or in a specific order?
No. You can take Core 1 and Core 2 in either order and on different dates; the certification is only awarded once you have passed both.
What topics make up the largest share of the Core 1 exam?
Hardware and hardware/network troubleshooting make up the largest portions of Core 1, followed by networking; mobile devices and virtualization and cloud computing are smaller but still tested domains.