CompTIA A+ Core 1 Study Guide

By EarnITCerts · Written by a university IT & cybersecurity instructor who has passed 50+ certification exams

The CompTIA A+ certification requires passing two separate exams: Core 1 (220-1201) and Core 2 (220-1202). Both exams must be completed from the same V15 exam series. Core 1 focuses heavily on physical hardware, mobile connectivity, SOHO networking, and systematic hardware/network troubleshooting.

1. Display Technologies

• LCD (IPS vs. TN vs. VA): Requires a dedicated backlight. IPS (In-Plane Switching) offers superior color accuracy and wide viewing angles; TN (Twisted Nematic) offers fast response times and low cost but poor viewing angles.
• OLED / AMOLED: Emits light directly from each organic pixel—no backlight required. Delivers true blacks, infinite contrast ratios, and thinner panels, though susceptible to screen burn-in.
• Mini-LED: Uses thousands of tiny LEDs for local dimming zones behind an LCD panel, drastically improving brightness and contrast.

2. Mobile Connectivity, Accessories & MDM

• Docking Station vs. Port Replicator: Both expand ports over USB-C/Thunderbolt, but a Docking Station provides desktop-class expansion (often supporting PCIe lanes, dedicated power delivery, and multiple independent external displays), whereas a Port Replicator simply passes through basic USB/peripheral ports.
• Cellular Standards: eSIM (embedded programmable SIM chip on the motherboard) vs. removable physical Nano-SIM; PRL (Preferred Roaming List) updates enable phones to locate the best cellular towers.
• MDM (Mobile Device Management): Centralizes corporate policies on BYOD and COPE (Corporate-Owned, Personally Enabled) devices—enforcing screen locks, geofencing, remote wipes, containerization, and app whitelisting.

1. Core Network Ports & Protocols for A+

2. IPv4 Addressing, APIPA & DNS Records

• Private IPv4 Ranges (RFC 1918):
  • Class A: 10.0.0.0 – 10.255.255.255 (/8)
  • Class B: 172.16.0.0 – 172.31.255.255 (/12)
  • Class C: 192.168.0.0 – 192.168.255.255 (/16)
• APIPA (Automatic Private IP Addressing): 169.254.x.x. Assigned automatically by the OS when a DHCP server cannot be reached. Allows local link communication only—no internet routing.
• Loopback Address: 127.0.0.1 (IPv4) or ::1 (IPv6). Used to test if the local TCP/IP stack is functioning.
• DNS Records: A (Hostname to IPv4), AAAA (Hostname to IPv6), MX (Mail Exchange server), CNAME (Canonical alias), TXT (Verification, SPF, and DKIM anti-spoofing records), PTR (Reverse DNS lookup).

3. 802.11 Wi-Fi Standards & Power Over Ethernet (PoE)

• PoE Standards: 802.3af (PoE: 15.4W), 802.3at (PoE+: 30W), and 802.3bt (PoE++: 60W–100W). Powers VoIP phones, wireless access points, and PTZ security cameras over twisted-pair Ethernet.

1. Copper & Fiber Cabling

• Twisted Pair Ethernet:
  • Cat 5e: 1 Gbps up to 100 meters.
  • Cat 6: 1 Gbps up to 100m; 10 Gbps up to 55 meters.
  • Cat 6a: 10 Gbps up to the full 100 meters (500 MHz bandwidth).
  • Plenum-rated cable: Coated with fire-retardant fluoropolymer (FEP/low-smoke PVC) for installation inside HVAC air-return ceilings; prevents toxic fumes during a fire.
• Storage & Memory:
  • NVMe M.2 SSDs: Connect directly to the PCIe bus for multi-gigabyte/sec throughput; vastly faster than 2.5-inch SATA III SSDs (capped around 600 MB/s).
  • RAID Levels: RAID 0 (Striping—speed only, zero fault tolerance; 2+ drives), RAID 1 (Mirroring—50% capacity utilization; 2+ drives), RAID 5 (Striping with distributed parity—survives 1 drive failure; minimum 3 drives), RAID 10 / 1+0 (Nested mirror + stripe—fast and fault tolerant; minimum 4 drives).

2. Printer Technologies & The 7-Step Laser Imaging Process

Laser printers are heavily tested on Core 1. Memorize the exact sequence using the mnemonic: "Please Come Every Day To Clean Up":

1. Processing: The printer's formatter board converts the page data into a raster bitmap image in memory.
2. Charging (Conditioning): The primary corona wire (or charging roller) applies a uniform negative charge (approx. -600V) across the photosensitive imaging drum.
3. Exposing (Writing): The laser beam scans the drum, neutralizing the negative charge down to approx. -100V everywhere toner should stick.
4. Developing: Negatively charged toner particles jump from the developer roller onto the exposed (-100V) areas of the drum.
5. Transferring: The transfer roller (or transfer corona) applies a positive charge to the back of the paper, pulling the negatively charged toner off the drum onto the page.
6. Fusing: The fuser assembly uses high heat and pressure rollers to permanently melt the plastic toner resin into the paper fibers.
7. Cleaning: A rubber wiper blade scrapes residual toner off the drum, and an erase lamp neutralizes any remaining electrical charge.

1. Hypervisors (Type 1 vs. Type 2)

• Type 1 (Bare-Metal Hypervisor): Installs directly onto physical server hardware without a host OS. Examples: VMware ESXi, Microsoft Hyper-V Server, Citrix Hypervisor, KVM. Used in enterprise datacenters.
• Type 2 (Hosted Hypervisor): Runs as an application inside a standard desktop operating system. Examples: Oracle VirtualBox, VMware Workstation/Fusion, Parallels. Used for local testing and labs.
• Hardware Requirements for Virtualization: Requires CPU virtualization extensions enabled in UEFI/BIOS (Intel VT-x or AMD AMD-V), ample RAM allocation, and fast storage IOPS.

2. Cloud Service & Deployment Models

• Service Models: IaaS (Infrastructure: virtual switches, VMs, raw block storage), PaaS (Platform: managed runtime environments for developers), SaaS (Software: turnkey web apps like Microsoft 365, Google Workspace).
• Core Cloud Characteristics: Rapid Elasticity (automatically scaling resources out and in based on real-time demand), Metered Service (pay-as-you-go billing), Multitenancy (multiple customers sharing underlying physical hardware securely), and High Availability.

1. The Official CompTIA 6-Step Troubleshooting Methodology

1. Identify the problem: Question the user, identify recent changes, check error logs, and perform backups before making modifications.
2. Establish a theory of probable cause: Always "question the obvious" first (e.g., is it plugged in? Is Airplane Mode turned on?).
3. Test the theory to determine cause: If the theory is confirmed, proceed to Step 4. If disproved, establish a new theory or escalate.
4. Establish a plan of action to resolve the problem and implement the solution: Follow corporate change management procedures.
5. Verify full system functionality and, if applicable, implement preventive measures: Ensure the user can perform their actual workflow.
6. Document findings, actions, and outcomes: Update the help desk ticketing system and knowledge base.

2. Hardware & Network Diagnostic Tools

• Cable Tester vs. Toner Probe: A Cable Tester verifies pin-to-pin continuity and detects split pairs or shorts on a known cable; a Toner Generator and Probe ("Fox and Hound") traces an unlabeled cable inside a wall or patch panel using an audible induction tone.
• Loopback Plug: Plugs into a physical NIC port to test whether the transceiver circuitry can transmit and receive signals.
• Wi-Fi Analyzer: Scans local wireless spectrum to identify overlapping channels (remember: the only non-overlapping 2.4 GHz channels are 1, 6, and 11).
• POST Card & Beep Codes: Diagnoses motherboard boot failures before video output initializes. Continuous beeps or repeating short beeps typically indicate unseated or faulty RAM; a clicking noise from a chassis indicates a failing mechanical HDD read/write actuator arm.

1. SOHO Router Configuration PBQs: Expect to configure a wireless router interface. Check three things first: set encryption to WPA2-AES or WPA3, place 2.4 GHz on channel 1, 6, or 11, and ensure the DHCP pool does not overlap with static server IPs.
2. Custom PC Build PBQs: When dragging and dropping components for two different workstation builds:
   • Gaming / CAD Workstation: Discrete high-wattage GPU, dual-channel DDR5 RAM, liquid/heavy cooling, high-wattage PSU.
   • Virtualization / Thick-Client Host: Maximum RAM capacity and multi-core CPU with virtualization extensions.
   • Home Theater PC (HTPC): Compact Mini-ITX form factor, quiet cooling, HDMI 2.1 audio/video support.
3. T568A vs. T568B Cable Termination PBQ: Memorize the pinouts! Both standards keep Blue on pins 4–5 and Brown on pins 7–8; they simply swap the Green and Orange pairs on pins 1–2 and 3–6. T568B starts with White/Orange, Orange on pins 1 and 2.