A security architect protects a public web application with a perimeter firewall, a web application firewall, host-based firewalls and endpoint detection on its servers, so that the failure of one control does not expose the application. Which of the following concepts does this design apply?
Choose one.
Defense in depth layers multiple, ideally different, controls around an asset so that a single failure does not lead to compromise.
The deciding detail is the stated goal: the failure of one control must not expose the application. That is the reason for layering. Zero Trust is tempting because it is also a modern architecture term, but it is about verifying every request rather than adding layers; least privilege and separation of duties are about permissions and people.
- Notice that several controls protect the same asset.
- Notice the goal: no single failure exposes it.
- Match 'layers so one failure is not fatal' to defense in depth.
- Rule out the permission- and people-focused principles.
Exam tip: Defense in depth = several layers, so one failed control is not a breach.
Security+ SY0-801 Security Controls: Categories, Types, CIA, AAA and Zero Trust — the lesson that teaches this.