Thanks to Villanova's \href{https://library.villanova.edu/amp/index.html}{\textcolor{blue}{Affordable Materials Project (AMP)}}, get the textbook \href{https://go.oreilly.com/villanova-univ/https://learning.oreilly.com/library/view/computer-networks-5th/9780123850591}{\textcolor{blue}{FREE HERE}}. This link is also posted on the Blackboard page for the course. The O'Reilly Media mobile app (iOS, Android \& Amazon Fire) allows you to read the textbook online/offline and syncs your progress and highlighted material across devices. Printed copies are not free.