Since the Network+ exam covers a wide spectrum of networking topics on its blueprint, you should have a CompTIA Approved book that targets the N10-006 exam. CompTIA's approval ensures that the book covers all topics on the exam blueprint.
Alternately, if you have a training budget, you might prefer to take a class, in which you can interact with your instructor and follow other students, ask questions, and get hands-on experience with the equipment you are studying.
Hands-on experience can also assist you in preparing for the exam. Use a couple of old PCs (one running Microsoft Windows® 7 or 8, and the other running a free Linux distribution of your choice), an older (less expensive) Cisco Ethernet switch, and a home wireless router to build a practice network topology. Practice Windows® and Linux commands and become comfortable configuring network options (for example, configuring a static IP address, default gateway, and DNS), and troubleshoot any issues you encounter as you build and work with your home lab. A small wireless router would also allow you to practice with the frequencies, security, 802.11 protocols, and other settings that will assist you in being ready for the exam.
To prepare for the subnet questions you might face, you can make up your own questions. For example, the company in the topology in Figure 1 wants to use the address space of 10.1.2.0/24 for its three sites.
Figure 1 Sample topology, with LAN and WAN connections.
You could make up questions such as “What subnet mask could be used to create four new subnets?” or “What mask would support 16 hosts?” Then you could use a free subnet calculator from the Internet to check your answers.