This app is created by a CompTIA A+, Network+, Security+, & Server+ certified IT professional with 20 years of experience to help users master the OSI Model prior to testing for a certification. It features 65 Questions in several easy to master formats, including True & False. It also features a timer to aid you in completing a daily recommended goal of 5 minutes so you can tackle your next certification with ease! This app is Advertisement free & collects no user data at any time.