In Kubernetes, application traffic flows through a well-defined set of API objects and runtime components before reaching a running container. Understanding this logical chain is essential for grasping how Kubernetes networking works internally.
The given sequence is: Gateway API → Service → EndpointSlice → Container. While this looks close to correct, it is missing a critical Kubernetes abstraction: the Pod. Containers in Kubernetes do not run independently; they always run inside Pods. A Pod is the smallest deployable and schedulable unit in Kubernetes and serves as the execution environment for one or more containers that share networking and storage resources.
The correct logical chain should be:
Gateway API → Service → EndpointSlice → Pod → Container
The Gateway API defines how external or internal traffic enters the cluster. The Service provides a stable virtual IP and DNS name, abstracting a set of backend workloads. EndpointSlices then represent the actual network endpoints backing the Service, typically mapping to the IP addresses of Pods. Finally, traffic is delivered to containers running inside those Pods.
Option A (Proxy) is incorrect because while proxies such as kube-proxy or data plane proxies play a role in traffic forwarding, they are not Kubernetes API objects that represent application workloads in this logical chain. Option B (Docker) is incorrect because Docker is a container runtime, not a Kubernetes API object, and Kubernetes is runtime-agnostic. Option D (Firewall) is incorrect because firewalls are not core Kubernetes workload or networking API objects involved in service-to-container routing.
Option C (Pod) is the correct answer because Pods are the missing link between EndpointSlices and containers. EndpointSlices point to Pod IPs, and containers cannot exist outside of Pods. Kubernetes documentation clearly states that Pods are the fundamental unit of execution and networking, making them essential in any accurate representation of application traffic flow within a cluster.
