CompTIA Network+ Practice Test

Which layer of the OSI model can be considered as the 'post office' for delivering packets?

1. Transport layer

2. Data Link layer

3. Network layer

4. Session layer

The correct answer is: Transport layer

The correct answer is the Network layer, which is often referred to as the 'post office' of the OSI model because it is responsible for the routing and forwarding of packets from the source to the destination across multiple networks. This layer manages addressing, enabling the identification of devices on the network, and ensures that packets are properly directed through various routers, similar to how a post office sorts and delivers mail to specific addresses. The Transport layer, which is indicated in the chosen response, is concerned with end-to-end communication and data flow control but does not handle the actual delivery of packets between networks. Instead, it focuses on ensuring complete data transfer and reliability of the connection. The Data Link layer is responsible for node-to-node data transfer and the physical addressing, such as MAC addresses, but does not manage the delivery of packets over multiple networks. The Session layer is mainly involved with establishing, managing, and terminating sessions between applications. It does not participate in the actual delivery of packets. Understanding these distinctions helps clarify why the Network layer is analogous to a 'post office' in the OSI model.