What are two benefits of using a layered network model?

The benefits of using a layered network model are significant in terms of network design and functionality. One of the primary advantages is that it prevents technology in one layer from affecting other layers. This segmentation means that changes or failures in one layer—whether it's the hardware, protocols, or transmission mediums—do not directly impact the other layers. This modular approach allows network designers and engineers to manage complexities more effectively and isolate issues or improvements within a specific layer.

Additionally, layered models assist in protocol design by providing a clear structure for interaction between different protocols. This means that developers can create protocols that function independently yet are compatible across layers, enabling more straightforward integration and innovation.

While other options touch on valid points, such as troubleshooting and cost reduction, they do not capture the primary feature of the layered model as effectively as the isolation of technology impacts among layers. Simplified troubleshooting does stem from this isolation, but it's a secondary benefit rather than the defining trait of the model. Reducing overall costs can occur as a result of streamlined design and maintenance, but it's not the inherent purpose of a layered approach.