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CompTIA A+ Core 1 (220-1201) Cheatsheet — 16 High-Yield Sections

Fast recall for 220-1201 across 16 concise sections: ports, Ethernet, fiber, connectors, Wi-Fi, security, IPv4/DHCP/DNS, net triage, RAID, filesystems, printers, displays, mobile, virtualization/cloud, Windows CLI, and ESD/safety plus troubleshooting.

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Use this for last-mile review. Star weak rows and re-drill with practice.

1) Ports & Protocols (memorize)

Service Port/Proto Notes
HTTP / HTTPS 80 TCP / 443 TCP Web; HTTPS uses TLS
SSH 22 TCP Secure shell / SFTP
FTP / FTPS / SFTP 20–21 TCP / 990 TCP / 22 TCP Legacy vs TLS vs SSH
SMTP / Submission 25 / 587 TCP Outbound email
POP3 / IMAP4 (+TLS) 110 / 143 (995 / 993) TCP Mail retrieval
RDP 3389 TCP/UDP Remote desktop
DNS 53 UDP/TCP Name resolution
DHCP 67/68 UDP Server/client
SNMP 161/162 UDP Monitor / traps
LDAP / LDAPS 389 / 636 TCP Directory

2) Ethernet Cabling & Standards

Std Speed Max Dist Cable
100BASE-TX 100 Mbps 100 m Cat5/5e
1000BASE-T 1 Gbps 100 m Cat5e/6
10GBASE-T 10 Gbps 55 m (Cat6) / 100 m (Cat6a) Cat6/6a

3) Fiber & Transceivers

Type Mode Connector Range
MMF Multi-mode LC/SC Short (LED/VCSEL)
SMF Single-mode LC/SC Long (laser)

Notes: SFP/SFP+ modules match fiber type; clean ends; avoid tight bends.

4) Peripheral & Storage Connectors

  • USB: 2.0 (480 Mbps), 3.2 Gen1 (5 Gbps), Gen2 (10), Gen2x2 (20). USB-C supports alt-modes (DP/Thunderbolt).
  • Display: HDMI • DisplayPort (DP++) • DVI-D/I • VGA (legacy).
  • Storage: SATA (data 7-pin, power 15-pin), M.2 keys (B/M), NVMe over PCIe.
  • Thunderbolt 3/4: USB-C, up to 40 Gbps.

5) Wi-Fi Standards

Std Bands Max PHY (theoretical) Notes
802.11n (Wi-Fi 4) 2.4/5 ~600 Mbps MIMO
802.11ac (Wi-Fi 5) 5 ~6.9 Gbps MU-MIMO, wide channels
802.11ax (Wi-Fi 6/6E) 2.4/5/(6E) >9 Gbps OFDMA, dense env.

6) Wi-Fi Security & SOHO Hygiene

  • Security order (best→worst): WPA3 → WPA2 (AES/CCMP) → WPA (TKIP) → WEP (avoid).
  • SOHO basics: change defaults, WPA2/3-Personal, strong passphrase, firmware updates, disable WPS.

7) IPv4, DHCP & DNS Essentials

  • Private ranges: 10.0.0.0/8 • 172.16.0.0–172.31.255.255 (/12) • 192.168.0.0/16
  • APIPA: 169.254.0.0/16 → DHCP failure (local-only).
  • Quick tells: Names fail but IP works → DNS issue; duplicate IP → intermittent drops.

8) Network Triage (first moves)

  • APIPA: Check DHCP scope/reachability/relay, VLAN, gateway/DNS.
  • No network: Verify link light, NIC enablement, cabling/port.
  • Wi-Fi slow: Prefer 5/6 GHz, right channel width, reduce interference; disable WPS.

9) RAID Levels

RAID Disks Benefit Notes
0 2+ Performance No redundancy
1 2 Redundancy 50% capacity
5 3+ Redundancy + perf 1 disk fault tolerant
10 4+ Redundancy + perf Mirrored stripes

10) Filesystems & Storage Health

  • FS: NTFS (permissions, quotas, EFS), exFAT (flash), FAT32 (legacy).
  • SMART warnings: Back up, replace drive.
  • M.2/NVMe: Seat fully; confirm BIOS/UEFI detection; check boot order.

11) Printers — Laser Process & Fixes

Order: Processing → Charging → Exposing → Developing → Transferring → Fusing → Cleaning

Symptom Likely Cause First Step
Streaks/lines Drum/toner/fuser residue Clean/replace unit
Ghosting Drum/fuser not discharging Replace drum/fuser
Jams Rollers/path/humidity Clear path; clean rollers
Faint/uneven Low toner/transfer Replace toner; check transfer roller

12) Displays & Graphics

Symptom Cause Quick Action
No signal Loose cable / GPU not seated Reseat cables/GPU; check input
Artifacts/tearing Driver or cable Update driver; swap cable/port
Dim image Backlight/power Adjust brightness; test external
Color shift Profile/cable Reset profile; try HDMI/DP

13) Mobile Devices

  • Connectivity: Tethering vs hotspot; Wi-Fi calling.
  • Accessories: NFC, Bluetooth profiles (A2DP/HFP).
  • Triage: Safe mode (Android), DFU/Recovery (iOS), clear app cache/data, battery health.

14) Virtualization & Client Cloud

  • Type 1 vs Type 2 hypervisors (bare-metal vs hosted).
  • VM resources: vCPU, memory ballooning, vNICs.
  • Snapshots ≠ backups (short-term only).
  • Cloud use: Storage sync (OneDrive/Drive), thin clients, basic VDI awareness.

15) Windows CLI & Tools

Need Tool/Command Use
IP stack ipconfig /all DHCP/DNS/gateway check
Reachability ping, tracert Latency, path issues
Name resolution nslookup DNS testing
Shares net use Map drives; creds
Disk chkdsk, diskpart, defrag Filesystem/partition
System health sfc /scannow, DISM /restorehealth Image repair
Logs Event Viewer System/Application issues

16) ESD/Safety & Troubleshooting Method

ESD & safety: Strap to ground, antistatic mat, handle by edges, ESD bags; surge/UPS; toner cleanup with cold water/ESD-safe vac.

Method (always show this logic):

  1. Identify the problem (gather, duplicate, what changed).
  2. Establish a probable cause (theory).
  3. Test the theory → confirm root cause.
  4. Plan and implement the fix.
  5. Verify full functionality; implement prevention.
  6. Document findings/actions/outcomes.

Golden rules: Start least intrusive, change one thing at a time, preserve data and user impact awareness.

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