CompTIA A+ Core 1 Flashcards Part 1

Port 20/21

FTP (File Transfer Protocol) - 20 = Data, 21 = Control

Port 22

SSH - Encrypted remote access

Port 23

Telnet - Unencrypted remote terminal

Port 25

SMTP - Sends email

Port 53

DNS - Name resolution (translates domain names to IPs)

Port 67/68

DHCP - Assigns IP addresses automatically

Port 80

HTTP - Unsecured web traffic

Port 110

POP3 - Downloads email to local client

Port 143

IMAP - Synchronizes email between client/server

Port 443

HTTPS - Secure web traffic

Port 3389

RDP - Remote Desktop Protocol

802.11a

5 GHz, 54 Mbps, short range

802.11b

2.4 GHz, 11 Mbps

802.11g

2.4 GHz, 54 Mbps, backward compatible with b

802.11n

2.4 GHz / 5 GHz, up to 600 Mbps, MIMO support

802.11ac

5 GHz, 1 Gbps+, MU-MIMO, beamforming

802.11ax (Wi-Fi 6)

2.4 + 5 GHz, OFDMA, more efficiency

ipconfig

Show Windows IP config

ifconfig

Show network interfaces (Linux/macOS)

ping

Test connectivity

tracert / traceroute

Show packet path

netstat

Show active connections

nslookup

Query DNS

arp -a

Show MAC-IP mappings

SATA

Drive interface for HDD/SSD

NVMe (M.2)

PCIe-based SSD, much faster than SATA

DDR3 vs DDR4

DDR4 = faster, lower voltage, not compatible

ATX PSU Wattage Rule

Choose PSU rated 30% above demand

PCIe Slot

Expansion slot for GPUs/NICs

USB 2.0 / 3.0 / 3.1 / 3.2 / USB-C

Increasing speeds with newer versions

VGA / DVI / HDMI / DisplayPort

Display connections (HDMI & DP carry audio)

RAID 0

Striping, high speed, no redundancy

RAID 1

Mirroring, redundancy, slower writes

RAID 5

Striping + parity (≥ 3 disks)

RAID 10 (1+0)

Mirrored pairs striped together (≥ 4 disks)

Troubleshooting Steps (CompTIA method)

1️⃣ Identify the problem 2️⃣ Establish a theory 3️⃣ Test the theory 4️⃣ Establish a plan 5️⃣ Verify full functionality 6️⃣ Document findings

Multimeter

Test voltage/resistance

Tone Generator & Probe

Trace cables

Loopback Plug

Test network ports/NICs

POST Card

Diagnose motherboard errors

Crimper

Terminate RJ-45 connectors

Boot failures

PSU, RAM, POST beeps, or video output

No network access

Check IP, link lights, NIC drivers

Hotspot/Tethering

Share mobile data

Airplane Mode

Disables radios

Mobile VPN

Encrypts traffic

Display Problems

Replace LCD/OLED/inverter

Touchscreen Issues

Recalibrate or replace digitizer

Battery Swelling

Replace immediately

Sync Settings

Cloud account sync for email/contacts/calendar

iOS vs Android Backup

iCloud vs Google Drive

IaaS

Virtual machines, storage, networking (e.g. AWS EC2)

PaaS

Developer platform (e.g. Azure App Service)

SaaS

Hosted apps (e.g. Gmail, Office 365)

Private Cloud

Dedicated to one organization

Public Cloud

Shared, multi-tenant

Hybrid Cloud

Mix of public + private

Community Cloud

Shared among similar orgs

Can connect to LAN but not Internet

Gateway or DNS misconfig

Ping IP works, domain fails

DNS issue

No shared printer access

File sharing off or discovery disabled

Link light off

Cable or NIC issue

No IP assigned

DHCP down/unreachable

IP conflict warning

Duplicate static IP

Wi-Fi connected, no Internet

Bad gateway or ISP outage

Slow Wi-Fi

Channel interference (change channel 1/6/11)