What does a defense-in-depth security strategy involve?
A.Deploying the strongest possible single firewall at the network edge
A single strong perimeter is the opposite — one failure point.
B.Multiple independent layers of security controls so a breach of one layer doesn't expose the whole system
Layered, redundant controls across seven levels. Correct.
C.Moving all workloads on-premises where they can be physically guarded
Location doesn't matter — the principle applies to any environment.
D.Relying on Microsoft to secure everything above the physical layer
Shared responsibility still leaves identity, data, and access to the customer.
Why this answer
Defense in depth layers controls — physical, identity & access, perimeter, network, compute, application, data — so attackers must defeat multiple independent defenses. The classic AZ-900 diagram is the concentric-ring model with data at the center.
Correct answer: B · Last reviewed 2026-02-13
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