Platform & DevOps·Traffic into and inside the cluster
the balancer picks a backend per TCP connection and never looks inside, so it cannot route on a path or retry a request.
Layer 4 load balancing
Also calledL4 load balancing, TCP load balancing, transport-layer balancing
Distributing traffic by connection at the transport layer, without parsing what is being carried. It is fast, protocol-agnostic and cheap, and it is blind: no path-based routing, no header inspection, no per-request retry, and no rebalancing of a connection once established. That last property is why one long-lived multiplexed connection sends every request to a single backend regardless of load.