Networking
L4 vs L7 Load Balancing
L4 routes on IP and port without reading the payload; L7 parses HTTP and can route by path, host or header.
Why interviewers ask about it
The strongest argument for L7 is health checking: a deadlocked process still accepts TCP connections, so only an application-level check knows it cannot serve.
This term is part of the free System Design interview preparation module - browse the full glossary for every definition.