To answer this question, you need to understand the OSI (Open Systems Interconnection) model. The OSI model is a conceptual framework that standardizes the functions of a communication system into seven distinct layers.
Let's go through each option to understand why it is correct or incorrect:
Option A) physical - This option is incorrect because the physical layer is responsible for the actual transmission and reception of data bits over a physical medium, such as cables or wireless signals.
Option B) transport - This option is incorrect because the transport layer is responsible for reliable end-to-end data delivery. It ensures that data is delivered error-free, in the correct order, and with flow control and congestion control mechanisms. Examples of protocols that operate at the transport layer include TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).
Option C) network - This option is correct because routers operate at the network layer. The network layer is responsible for logical addressing, routing, and the delivery of packets from the source to the destination across multiple networks. Routers examine the destination IP address in the packet's header and make decisions on how to route the packet to its destination.
Option D) MAC sublayer of the data link layer - This option is incorrect because the MAC (Media Access Control) sublayer is a component of the data link layer, which is responsible for node-to-node data transfer. The MAC sublayer is primarily concerned with the control of access to the physical medium and the addressing of devices on a local network. Ethernet is an example of a protocol that operates at the data link layer.
The correct answer is C) network. Routers operate at the network layer and are responsible for routing packets between networks based on the destination IP address.