CompTIA Network+ Study Guide

Preparing for the CompTIA Network+ (N10-009)? You are in the right place. This is the written companion to the practice exams, a complete walk through everything the test covers, gathered in one place.

Network+ is a vendor-neutral, foundational networking certification, and the exam mixes two kinds of thinking. Part of it is recall: port numbers, the seven OSI layers, and subnetting arithmetic you have to know cold. The larger part is scenario judgment, where a stem hands you a constraint or a symptom and asks for the best move. One habit answers many of those: name the OSI layer first, because the layer pins the fix, so a reachable but slow link is usually a Layer 1 or 2 fault, not a routing problem. Many items also turn on a clean choose-between decision: TCP for guaranteed delivery versus UDP for low-latency speed, or a hot site versus a cold site for a given RPO and RTO target.

The guide follows the five official domains, weighted the way the real exam weighs them: Network Troubleshooting (24%) and Networking Concepts (23%) carry the most marks, then Network Implementation (20%), Network Operations (19%), and Network Security (14%). Each chapter builds the mental model in plain language, separates the look-alike options with comparison tables and decision trees, and ends with a cheat sheet of the numbers and traps worth carrying into the test room. Start at the top to read straight through, or pick a domain from the list beside this page.