The facts A+ candidates most often need to memorize, on one printable page: ports, Wi-Fi standards, cables, RAID, IP ranges and printer care for Core 1 (220-1201), then Windows and Linux commands, file systems, malware removal, security and backups for Core 2 (220-1202). Every list is checked against CompTIA's current objectives, so topics they dropped, like the laser imaging process, are left off.
How to use this sheet
What's on the sheet follows CompTIA's 220-1201 (V15) objectives, document version 4.0 and 220-1202 objectives (version 2.0); the explanations are ours. Print it from your browser (it prints without the site's menus), or quiz yourself: cover the right-hand column and say the answer.
Core 1: ports and protocols
Ports in the 220-1201 objectives
Port
Protocol
TCP/UDP
20-21
FTP
TCP
22
SSH
TCP
23
Telnet
TCP
25
SMTP
TCP
53
DNS
UDP (TCP for zone transfers and large replies)
67/68
DHCP
UDP
80
HTTP
TCP
110
POP3
TCP
137-139
NetBIOS/NetBT
UDP 137-138, TCP 139
143
IMAP
TCP
389
LDAP
TCP
443
HTTPS
TCP
445
SMB/CIFS
TCP
3389
RDP
TCP (newer clients also use UDP)
The full ports guide has what each protocol does, the secure pairs and ways to remember them.
Core 1: Wi-Fi standards
802.11 standards (theoretical maximum speeds)
Standard
Name
Bands
Max speed
802.11a
—
5 GHz
54 Mbps
802.11b
—
2.4 GHz
11 Mbps
802.11g
—
2.4 GHz
54 Mbps
802.11n
Wi-Fi 4
2.4 and 5 GHz
600 Mbps
802.11ac
Wi-Fi 5
5 GHz
About 6.9 Gbps
802.11ax
Wi-Fi 6 / 6E
2.4 and 5 GHz; 6E adds 6 GHz
About 9.6 Gbps
802.11be
Wi-Fi 7
2.4, 5 and 6 GHz
About 46 Gbps
Real-world speeds are much lower than these maximums. 220-1201 also covers the 2.4, 5 and 6 GHz bands, channels and channel widths, Bluetooth, NFC and RFID.
T568A, pins 1-8: white/green, green, white/orange, blue, white/blue, orange, white/brown, brown. T568A on one end and T568B on the other makes a crossover cable.
Fiber: single-mode carries one light path over long distances (kilometers, laser light); multimode carries many paths over shorter runs (hundreds of meters, LED or VCSEL light).
Other network cable terms: coaxial (F-type connector), unshielded twisted pair (UTP) for most Ethernet, shielded twisted pair (STP) for electrical noise, direct burial for outdoor runs in the ground, and plenum-rated jackets for air-handling spaces.
Peripheral and drive cables: USB 2.0 runs at 480 Mbps and USB 3.0 at 5 Gbps; Thunderbolt 3 and 4 reach 40 Gbps over a USB-C connector; SATA connects internal drives and eSATA external ones.
Video: HDMI and DisplayPort are digital and carry audio; DVI carries digital (and on DVI-I, analog) video without audio; VGA is analog only; USB-C can carry DisplayPort video.
Connector types in the 220-1201 objectives
Connector
Used for
RJ11
Phone line and DSL; 6-position plug with 2 or 4 contacts, narrower than RJ45
RJ45
Ethernet twisted pair; 8 positions
F-type
Coaxial cable for cable internet and TV; screws on
ST (straight tip)
Fiber; round bayonet that twists to lock
SC (subscriber connector)
Fiber; square, push-pull
LC (Lucent connector)
Fiber; small form factor with a latch, often in duplex pairs
Punchdown block
Terminates twisted-pair wires in a wiring closet or patch panel
MicroUSB
Older Android phones and small devices
MiniUSB
Older cameras, controllers and peripherals
USB-C
Reversible connector for data, video and charging
Molex
4-pin internal power for older drives and fans
Lightning
Apple's proprietary connector on older iPhones and iPads
DB9
9-pin serial port for console and legacy devices
Core 1: RAM, storage and RAID
DIMM vs SODIMM: DIMMs go in desktops, the shorter SODIMMs in laptops and small form factor PCs.
DDR generations: DDR3 uses 240-pin DIMMs and 204-pin SODIMMs at 1.5 V; DDR4 uses 288-pin DIMMs and 260-pin SODIMMs at 1.2 V; DDR5 uses 288-pin DIMMs and 262-pin SODIMMs at 1.1 V. Each generation is keyed differently, so none fits another's slot.
ECC RAM detects and corrects single-bit memory errors; servers use it, most desktops don't. Channels: matched modules in the right slots run in dual or quad channel for more bandwidth.
Hard drives: 5,400, 7,200, 10,000 and 15,000 rpm spindle speeds, in 2.5-inch and 3.5-inch sizes. SSDs connect over NVMe (on PCIe), SATA or SAS, in M.2, mSATA or drive-bay form factors.
RAID levels in the 220-1201 objectives
Level
Min drives
How it works
Survives
Usable space
RAID 0
2
Striping
No drive failure
100% of total
RAID 1
2
Mirroring
All but one drive
50% with two drives
RAID 5
3
Striping with distributed parity
One drive
Total minus one drive
RAID 6
4
Striping with double parity
Two drives
Total minus two drives
RAID 10
4
A stripe of mirrors (1+0)
One drive per mirrored pair
50% of total
Core 1: IP addressing
Address ranges to know
Address or range
What it is
10.0.0.0 - 10.255.255.255 (10.0.0.0/8)
Private (class A range)
172.16.0.0 - 172.31.255.255 (172.16.0.0/12)
Private (class B range)
192.168.0.0 - 192.168.255.255 (192.168.0.0/16)
Private (class C range), the usual home and SOHO range
169.254.0.0 - 169.254.255.255
APIPA: Windows gives itself one of these when no DHCP server answers
127.0.0.1 (127.0.0.0/8)
IPv4 loopback (this computer)
::1
IPv6 loopback
fe80:: (fe80::/10)
IPv6 link-local, used only on the local network segment
A PC showing a 169.254 address with no default gateway didn't get an answer from DHCP: check the cable or Wi-Fi link and the DHCP server, then release and renew the lease.
Core 1: cloud and virtualization
Service models: IaaS rents servers, storage and networks (you run the OS); PaaS adds the platform to build and run apps on; SaaS is finished software you just use.
Cloud models: private (one organization), public (shared provider), hybrid (a mix) and community (shared by organizations with common needs).
Cloud characteristics: shared vs dedicated resources, metered utilization (including ingress and egress traffic), elasticity, availability, file synchronization and multitenancy.
Hypervisors: Type 1 runs directly on the hardware (bare metal); Type 2 runs as an app on a host OS. Also know virtual desktop infrastructure (VDI) and containers.
Core 1: networking tools
Networking tools in the 220-1201 objectives
Tool
What it does
Crimper
Attaches RJ45 or RJ11 plugs to cable ends
Cable stripper
Removes the outer jacket without nicking the wires
Wi-Fi analyzer
Shows nearby networks, channels and signal strength
Toner probe
Traces one cable through walls or a bundle by its tone
Punchdown tool
Seats wires into a punchdown block, patch panel or keystone jack
Cable tester
Checks each wire's continuity and the pinout
Loopback plug
Sends a port's output back to itself to test the port
Network tap
Copies traffic from a link so it can be monitored
Core 1: printer maintenance
Printer types and their maintenance (220-1201)
Printer
Parts to know
Maintenance
Laser
Toner cartridge, maintenance kit (fuser and rollers)
Replace toner, apply a maintenance kit, calibrate, clean
Inkjet
Ink cartridges, printhead, roller, feeder
Clean the printheads, swap cartridges, calibrate, clear paper jams
Thermal
Feed assembly, heating element, special thermal paper
Replace paper, clean the heating element, remove debris
Impact
Ribbon, printhead, multipart paper
Replace the ribbon, printhead and paper
No laser imaging steps. Older cheat sheets list the seven-step laser imaging process, from processing to cleaning. The imaging process isn't in the 220-1201 objectives, which cover laser printer maintenance instead: replacing toner, applying a maintenance kit, calibrating and cleaning.
The same goes for the six-step troubleshooting methodology: 220-1201 lists it as a best practice, not a tested objective. The troubleshooting methodology guide covers what changed.
Core 2: Windows commands
Windows command-line tools in the 220-1202 objectives
Command
Group
What it does
cd
Navigation
Change directory
dir
Navigation
List a directory's contents
ipconfig
Network
Show IP settings; /all for details, /release and /renew for DHCP, /flushdns
ping
Network
Test whether a host answers
netstat
Network
List connections and listening ports
nslookup
Network
Query DNS for a name or address
net use
Network
Map or disconnect a network drive
tracert
Network
List each router hop to a host
pathping
Network
Trace the route, then measure loss at each hop
chkdsk
Disk management
Check a disk for errors; /f fixes, /r also finds bad sectors
format
Disk management
Format a volume with a file system
diskpart
Disk management
Manage disks, partitions and volumes from the command line
md
File management
Make a directory
rmdir
File management
Remove a directory
robocopy
File management
Robust copy for large or repeated file copies
hostname
Informational
Show the computer's name
net user
Informational
List or manage local user accounts
winver
Informational
Show the Windows version and build
whoami
Informational
Show the signed-in account
[command] /?
Informational
Show a command's help and switches
gpupdate
OS management
Apply Group Policy now; /force reapplies everything
gpresult
OS management
Show which Group Policy settings apply
sfc
OS management
System File Checker; sfc /scannow repairs protected system files
Core 2: Windows tools
Task Manager, MMC snap-ins and other Windows tools in the 220-1202 objectives
Tool
What it's for
Task Manager
Processes, performance, startup apps, users and services
eventvwr.msc
Event Viewer: system, application and security logs
diskmgmt.msc
Disk Management: partitions, volumes, drive letters
taskschd.msc
Task Scheduler: run tasks on a schedule or trigger
devmgmt.msc
Device Manager: hardware and drivers
certmgr.msc
Certificate Manager: the user's certificates
lusrmgr.msc
Local Users and Groups
perfmon.msc
Performance Monitor: counters and logs over time
gpedit.msc
Local Group Policy Editor (not in Home editions)
msinfo32.exe
System Information: hardware and software summary
resmon.exe
Resource Monitor: live CPU, memory, disk and network use per process
msconfig.exe
System Configuration: boot options and services
cleanmgr.exe
Disk Cleanup: remove temporary and unneeded files
dfrgui.exe
Defragment and Optimize Drives
regedit.exe
Registry Editor
Core 2: Linux commands
Linux commands in the 220-1202 objectives
Command
Group
What it does
ls
File management
List files
pwd
File management
Print the working directory
mv
File management
Move or rename
cp
File management
Copy
rm
File management
Remove files (-r for directories)
chmod
File management
Change permissions
chown
File management
Change owner
grep
File management
Search text for a pattern
find
File management
Search for files
fsck
Filesystem management
Check and repair a file system
mount
Filesystem management
Attach a file system to the directory tree
su
Administrative
Switch user (root by default)
sudo
Administrative
Run one command with elevated rights
apt
Package management
Install and update packages on Debian and Ubuntu
dnf
Package management
Install and update packages on Fedora and Red Hat
ip
Network
Show and set addresses, links and routes
ping
Network
Test whether a host answers
curl
Network
Transfer data to or from a URL
dig
Network
Query DNS
traceroute
Network
List each hop to a host
man
Informational
Show a command's manual
cat
Informational
Print a file's contents
top
Informational
Live view of processes and resource use
ps
Informational
List processes
du
Informational
Disk usage of files and folders
df
Informational
Free space per file system
nano
Text editors
Simple terminal text editor
Linux configuration files in the 220-1202 objectives
File
What it holds
/etc/passwd
User accounts
/etc/shadow
Password hashes, hidden from normal users
/etc/hosts
Local hostname-to-address entries
/etc/fstab
File systems to mount at boot
/etc/resolv.conf
DNS servers to use
Core 2: file systems
File systems in the 220-1202 objectives
File system
Used by
Notes
NTFS
Windows
Permissions, encryption, compression, journaling; the default for Windows drives
ReFS
Windows (servers and storage pools)
Resilient File System, built for large volumes and data integrity
FAT32
Almost everything
Wide compatibility; 4 GB maximum file size
ext4
Linux
The common default Linux file system, with journaling
XFS
Linux
High-performance journaling file system for large files and volumes
APFS
macOS and iOS
Apple File System, optimized for SSDs, with snapshots and encryption
exFAT
Flash drives and memory cards
Works across Windows and macOS with no 4 GB file limit
Core 2: malware removal, in order
The 220-1202 objectives number the SOHO malware removal procedure in ten steps. The step names are CompTIA's:
Confirm the symptoms point to malware, not a hardware fault or unwanted but legitimate software
2. Quarantine infected system
Disconnect the PC from the network, shared drives and cloud sync so the infection can't spread
3. Disable System Restore in Windows Home
Turn off restore points so an infected snapshot can't bring the malware back
4. Remediate infected systems
Start the cleanup, which steps 5 to 7 carry out
5. Update anti-malware software
Get the latest scanning engine and definitions before you scan
6. Scan and removal techniques (safe mode, preinstallation environment)
Scan and remove, from safe mode or a preinstallation environment if the malware fights back
7. Reimage/reinstall
Wipe and reinstall when you can't trust the system to be clean
8. Schedule scans and run updates
Set recurring scans and patch the OS and apps
9. Enable System Restore and create a restore point in Windows Home
Turn restore points back on and create one of the clean system
10. Educate the end user
Explain how the infection got in and how to avoid it next time
The older 220-1102 list counted seven: updating and scanning were parts of its remediate step, and it had no reimage step. Practice the order in the free Remove Malware in Order PBQ.
Core 2: wireless security and authentication
Wireless protocols and authentication methods in the 220-1202 objectives
Term
What it is
WPA2
Wi-Fi Protected Access 2; AES with CCMP, the long-time standard
WPA3
Current Wi-Fi security; SAE replaces the pre-shared key handshake
TKIP
Older WPA encryption; deprecated and weak
AES
The strong encryption cipher WPA2 and WPA3 use
RADIUS
Central authentication server, often for enterprise Wi-Fi and VPN
TACACS+
Cisco-developed central authentication, mostly for network device logins
Kerberos
Ticket-based authentication in Windows Active Directory domains
Multifactor authentication
Two or more factor types: something you know, have or are
Core 2: backups and data destruction
Backup types and rotation schemes in the 220-1202 objectives
Backup
What it means
Full
Everything, every time; the slowest backup and the fastest restore
Incremental
Changes since the last full or incremental backup; restore needs the full plus every incremental since
Differential
Changes since the last full; restore needs the full plus the latest differential
Synthetic full
A full backup built from the last full and later incrementals, without rereading the source
Onsite vs offsite
Rotation: recent copies onsite for quick restores, others offsite so one disaster can't take them all
Grandfather-father-son (GFS)
Rotation: daily (son), weekly (father) and monthly (grandfather) backup sets
3-2-1 rule
Three copies of the data, on two kinds of media, one of them offsite
Data destruction and disposal in the 220-1202 objectives
Method or concept
What it means
Drilling
Physical: holes through the platters or chips
Shredding
Physical: an industrial shredder grinds the drive
Degaussing
Physical: a strong magnetic field wipes magnetic media (not SSDs)
Incineration
Physical: burning the drive
Erasing/wiping
Reuse: overwrite the data so it can't be recovered
Low-level formatting
Reuse: a full zero-fill of the drive (true low-level formatting is done only at the factory)
Standard formatting
Reuse: a new file system only; the data can often be recovered
Third-party vendor
Outsourcing: a company that destroys or recycles drives for you
Certification of destruction/recycling
Outsourcing: the vendor's proof that the drives were destroyed or recycled
Regulatory and environmental requirements
Laws and e-waste rules on how drives and data must be disposed of
Practice what's on the sheet
Free A+ practice test: the 60-question test covers both cores, with every answer explained.
Free PBQs:performance-based questions for both exams, including port matching and step-order questions, graded instantly.
Hands-on labs: the free A+ labs put the Windows commands and hardware facts to work on real faults.
Flashcards: the A+ flashcards guide turns lists like these into a daily routine.
Turn the sheet into recall.
Check yourself with a free A+ practice test, every answer explained. Then start the A+ course free: the first 4 sections of Core 1 and Core 2, plus every flashcard deck.
Yes, this page. It prints cleanly from your browser: the site's menus and buttons are left off, and the tables print in black and white. Choose Print, then Save as PDF to keep a copy.
Can I bring a cheat sheet into the A+ exam?
No. CompTIA doesn't allow notes or reference material in the exam. Pearson VUE gives you an erasable note board (a digital whiteboard if you test online), and many candidates write ports or step orders on it from memory once the exam starts.
What should I memorize for CompTIA A+?
The lists on this page: port numbers, Wi-Fi standards, cable categories and connectors, RAID levels, private and APIPA address ranges, Windows and Linux commands, file systems and the malware removal order. For the rest of the objectives, practice applying the ideas to scenarios rather than memorizing lists.
Is the laser printer imaging process on the A+ exam?
Not in the current objectives. 220-1201 (V15) lists laser printer maintenance, not the imaging steps older cheat sheets show. The imaging process is still useful background for troubleshooting print-quality problems.
How many steps are in the CompTIA malware removal process?
The 220-1202 objectives list ten steps, from investigating the symptoms to educating the end user. The older 220-1102 list had seven, with updating and scanning folded into remediation and no reimage step.
