Networking Master Guide (CompTIA A+ Study Hub)

This page organizes the networking topics on this site into a simple study path. If you're new to networking, start at the top and work down.

Recommended order: Subnet Mask → DHCP → DNS → APIPA → Common Ports

Beginner-friendly A+ focused Troubleshooting-first

Start Here: Core Concepts

Learn what “local vs remote” means and why the subnet mask affects routing and connectivity.

Best first topic — makes everything else easier.

Understand how devices automatically receive IP addresses, gateways, and DNS settings.

Know DORA and what a lease is.

See how domain names translate to IP addresses and why DNS causes “internet feels broken” issues.

Key troubleshooting clue: IP works, names don’t.

Learn why 169.254 appears and what it tells you about DHCP and connectivity problems.

If you see 169.254, think: DHCP failed.

Quick reference for high-yield ports like 80, 443, 53, 22, and 3389 with memory tips.

Easy points if you memorize the core list.

If you're studying consistently, practice tests + a structured guide will speed everything up.

169.254.x.x → DHCP not reachable → check cable/Wi-Fi/router → try ipconfig /renew

IP works but websites don’t → DNS issue → try different DNS (8.8.8.8) → ipconfig /flushdns

HTTP works, HTTPS fails → check port 443 / firewall rules