Explain what the OSI reference model is and why it is useful ?

The OSI model allows us to think about our network in chunks or layers. You can focus on securing each layer, optimizing each layer, and troubleshooting each layer.

Explanation:

While this model is not directly implemented in the TCP/IP networks that are most common today, it is a valuable conceptual model that helps you to relate different technologies to one another and implement the right technology in the right way. You will find references to the OSI model throughout vendor literature from vendors and also in our certification preparation materials, so it is important to understand what these references mean.

67 could been the answer as well