Guides
Study guides
Original explanations of topics that come up across CompTIA A+ and CompTIA Network+, written from primary sources and linked to them. New guides are added as the question bank grows.
All guides
- CompTIA A+ Core 1 · CompTIA Network+
What a 169.254.x.x address means, and how to fix it
Why a computer ends up with a 169.254 address, what it can and can't reach, and how to trace the DHCP problem behind it. - CompTIA A+ Core 1 · CompTIA Network+
Private IPv4 address ranges (RFC 1918), explained
The three private IPv4 blocks, how to recognize them at a glance, the 172.16/12 mistake almost everyone makes, and the ranges that look private but aren't.