iv Linda K. Lavender is an adjunct instructor of information technology for Tidewater Community College in Virginia Beach. She holds a Master of Science in cyber­ security and a Bachelor of Science in computer information systems from Saint Leo University. She has been named teacher of the year by several organizations, including ACTE, and received the Virginia Affiliate Educator Award of the NCWIT Award for Aspirations in Computing. She is certified in CompTIA Security+, Network+, A+, CySA+, and CTT+ Microsoft MCTS, MCTIP, MCP, MOS, and MTA and CIW Foundations. About the Author Intended Audience Security Essentials is designed for students, as well as professionals, preparing for the CompTIA Security+ SY0-601 Certification, one of the most sought-after entry- level certifications in digital and information security. Earning CompTIA Security+ certification validates baseline skills needed to become an IT security professional. The concepts discussed in this textbook build off an assumed understanding of computer systems, including operation, installation, troubleshooting, maintenance, and repair. Additionally, the reader should have foundational networking knowledge, such as topologies, installation, devices and media, IPv4 and IPv6 addressing, trou- bleshooting, administration, and management. An ideal user of this textbook is an information technology student or professional who has already obtained CompTIA A+ and Network+ Certifications, or the equivalent study or professional experience. Securing computing devices is an advanced topic, and it relies on a founda- tional knowledge of basic computer hardware, processing, and networking. As such, CompTIA recommends a minimum of two years in IT administration as well as a CompTIA Network+ Certification before sitting for the Security+ Certification Exam.