General approach and core use case
Tenable Nessus is primarily a network and host vulnerability assessment tool. It is widely considered for service enumeration, configuration checks, missing patches, and known-vulnerability detection across infrastructure.
That makes Nessus valuable for infrastructure hygiene and audit programs, but network checks and application DAST answer different questions. A web assessment must navigate application state, maintain authenticated sessions, observe browser behavior, exercise inputs and APIs, and retain request-level evidence for validation.