Explain the role of data classification and the responsibilities of the data owner versus the data custodian.

Classification is the foundation of the asset-security domain because you cannot protect data proportionally if you do not know how sensitive it is. Interviewers use this to test whether you understand both the rationale and the role separation.

Why classify

Classification assigns a sensitivity level — for example Public, Internal, Confidential, Restricted (commercial) or Unclassified, Confidential, Secret, Top Secret (government) — so that controls match value and risk. Without it you either under-protect crown-jewel data or over-spend locking down trivial information. The label then drives every downstream handling rule: encryption, access restrictions, retention periods, transmission rules, and secure disposal.

Owner versus custodian

This role split is the heart of the question:

• Data owner — a business/management role accountable for the data. The owner determines its classification, defines who may access it, and ultimately accepts the residual risk. Ownership is about authority and accountability, not day-to-day operations.
• Data custodian — typically an IT/operations role that implements and maintains the protections the owner mandates: backups, access provisioning, patching, and enforcing the controls. The custodian executes; it does not decide the classification.

Keeping these distinct prevents IT from quietly making business risk decisions it is not authorized to make.

The lifecycle angle

Classification is not one-time. As data moves through its lifecycle — creation, storage, use, sharing, archival, destruction — its label governs handling at each stage, including secure disposal so sensitive data does not leak through decommissioned media.

What interviewers look for

A clear "labels enable proportional controls" rationale, the owner-versus-custodian separation (business accountability versus technical implementation), and the insight that classification flows into handling, retention, and destruction across the whole data lifecycle.