CompTIA Network+ Practice Test

Which of the following best describes Layer 1 of the OSI model?

1. Transport Control Protocols

2. Physical connections and signaling methods

3. Data session management

4. Routing and addressing schemes

The correct answer is: Physical connections and signaling methods

Layer 1 of the OSI model is primarily concerned with the physical aspects of networking. This layer handles the transmission of raw bitstreams over a physical medium. It encompasses the hardware technologies that facilitate physical connections, such as cables, switches, and braiding, as well as the signaling methods used to send and receive these signals. This includes the voltage levels, timing of voltage changes, physical data rates, and the layout of pins, sockets, and cable specifications. In contrast, the other options refer to different layers or concepts within the OSI model. For instance, transport protocols fall under Layer 4, where data is segmented and managed for reliable transmission. Data session management relates to Layer 5, which deals with establishing, managing, and terminating connections between applications. Finally, routing and addressing are defined in Layer 3, focusing on how data packets are routed between devices on a network and addressing schemes that identify these devices. Thus, the correct choice encapsulates the core function of Layer 1, which is integral to the fundamental operation of networking.