Author of 10 editions of the best-selling CCNA books: The CCNA Official Cert Guides (OCG) from Cisco Press. At various times, authored introductory networking books, plus Cisco Press OCGs for the CCENT, CCNA, CCNP Route, CCNP QoS, and CCIE exams. Has worked as a network engineer, consultant, instructor, course developer, author, and now YouTuber (@NetworkUpskill).
