How do you effectively determine if the streamlined, four-layer TCP/IP model provides a better practical framework for modern internet communication than the theoretical seven-layer OSI model? Furthermore, every piece of data you send—from a simple WhatsApp message to a 4K Netflix stream—must be packetized, addressed, and routed through this specific hierarchy. Why is understanding the interplay between the Transport layer's reliability and the Internet layer's routing the most critical skill for troubleshooting today's global networks?