Which troubleshooting method typically starts at the Network Layer of the TCP/IP model and breaks the network into smaller segments for testing?

The method that starts at the Network Layer of the TCP/IP model and breaks the network into smaller segments for testing is known as "Divide and conquer." This method is effective for isolating problems within a network by systematically narrowing down the potential sources of issues. By focusing on smaller segments of the network, technicians can identify whether the issue resides within a specific segment or if it is more widespread.

In this method, starting at the Network Layer allows for testing routing and connectivity issues first before analyzing higher layers, which contain the actual end-user applications. This approach is particularly useful as it can help in pinpointing the exact location of the malfunction, allowing for quicker resolutions.

Other methods, such as top-down or bottom-up troubleshooting, focus on different perspectives of the network stack, but they do not specifically emphasize starting from the Network Layer to segment the network for targeted testing. This is why "Divide and conquer" is the most fitting answer for the question asked.