Routing, protocols, packet captures, load balancers, proxies. The difference between things working and things mysteriously not working — usually answered with tcpdump.
On Linux, a network interface is not necessarily a physical network card — it’s a kernel networking object. Some represent real hardware; others connect containers, attach VMs, create tunnels, carry VLANs, build overlays, or separate routing domains entirely.
QUIC did not choose UDP simply because “UDP is faster.” The bigger reason was architectural — TCP had become difficult to evolve because its transport logic lives deep inside operating-system kernels and decades of middleboxes had learned to expect TCP to behave in very specific ways.
QUIC and TCP are not interchangeable.
Even with optimized queries, fast APIs, and a CDN, your app may still be slow. Network protocols like TCP congestion control and BGP routing introduce latency beyond your code.
Layer 4 uses TCP/IP for simple, fast routing offering speed and efficiency, while Layer 7 enables smart routing with HTTP content inspection, providing intelligent routing and caching capabilities.