D is correct. Ingress is a Kubernetes API object that defines rules for external access to HTTP/HTTPS services in a cluster. The defining capability is Layer 7 routing—commonly host-based and path-based routing—so you can route requests like example.com/app1 to one Service and example.com/app2 to another. While the question mentions “based on their path,” that’s a classic and correct Ingress use case (and host routing is also common).
Ingress itself is only the specification of routing rules. An Ingress controller (e.g., NGINX Ingress Controller, HAProxy, Traefik, cloud-provider controllers) is what actually implements those rules by configuring a reverse proxy/load balancer. Ingress typically terminates TLS (HTTPS) and forwards traffic to internal Services, giving a more expressive alternative to exposing every service via NodePort/LoadBalancer.
Why the other options are wrong:
A suggests routing by IP address; Ingress is fundamentally about HTTP(S) routing rules (host/path), not direct Service IP access.
B and C describe non-HTTP protocols; Ingress is specifically for HTTP/HTTPS. For TCP/UDP or other protocols, you generally use Services of type LoadBalancer/NodePort, Gateway API implementations, or controller-specific TCP/UDP configuration.
Ingress is a foundational building block for cloud-native application delivery because it centralizes edge routing, enables TLS management, and supports gradual adoption patterns (multiple services under one domain). Therefore, the main purpose described here matches D.
=========
