Book excerpt: Network Fundamentals, CCNA Exploration Companion Guide is the official supplemental textbook for the Network Fundamentals course in the Cisco® Networking Academy® CCNA® Exploration curriculum version 4. The course, the first of four in the new curriculum, is based on a top-down approach to networking. The Companion Guide, written and edited by Networking Academy instructors, is designed as a portable desk reference to use anytime, anywhere. The book’s features reinforce the material in the course to help you focus on important concepts and organize your study time for exams. New and improved features help you study and succeed in this course: Chapter objectives–Review core concepts by answering the focus questions listed at the beginning of each chapter. Key terms–Refer to the updated lists of networking vocabulary introduced and highlighted in context in each chapter. Glossary–Consult the comprehensive glossary with more than 250 terms. Check Your Understanding questions and answer key–Evaluate your readiness with the updated end-of-chapter questions that match the style of questions you see on the online course quizzes. The answer key explains each answer. Challenge questions and activities–Strive to ace more challenging review questions and activities designed to prepare you for the complex styles of questions you might see on the CCNA exam. The answer key explains each answer. How To–Look for this icon to study the steps you need to learn to perform certain tasks. Packet Tracer Activities– Explore networking concepts in activities interspersed throughout some chapters using Packet Tracer v4.1 developed by Cisco. The files for these activities are on the accompanying CD-ROM. Also available for the Network Fundamentals Course Network Fundamentals, CCNA Exploration Labs and Study Guide ISBN-10: 1-58713-203-6 ISBN-13: 978-1-58713-203-2 Companion CD-ROM **See instructions within the ebook on how to get access to the files from the CD-ROM that accompanies this print book.** The CD-ROM provides many useful tools and information to support your education: Packet Tracer Activity exercise files v4.1 VLSM Subnetting Chart Structured Cabling Exploration Supplement Taking Notes: a .txt file of the chapter objectives A Guide to Using a Networker’s Journal booklet IT Career Information Tips on Lifelong Learning in Networking This book is part of the Cisco Networking Academy Series from Cisco Press®. The products in this series support and complement the Cisco Networking Academy online curriculum.