The main responsibility of the network layer is to insert information into the packet’s header so that it can be properly routed. The protocols at the network layer must determine the best path for the packet to take. The following answers are incorrect: Session layer. The session layer is responsible for establishing a connection between two applications. Physical layer. The physical layer if responsible for converting electronic impulses into bits and vice-versa. Transport layer. The transport layer is responsible for data transmission and error detection.
The following reference(s) were/was used to create this question: Source: HARRIS, Shon, All-In-One CISSP Certification Exam Guide, McGraw-Hill/Osborne, v3, chapter 7: Telecommunications and Network Security (page 422-428).
ISC2 Official ISC2 Guide to the CBK (OIG) 2007, p. 409-412