Auditors and security professionals usually prefer preventive controls over detective controls because they actually block unwanted events and prefer detective controls to deterrent controls because detective controls record events while deterrent controls do not. However, there are often circumstances where cost, resource, or technical limitations force an organization to accept a detective control when it would prefer a preventive one. For example, there is no practical way to build a control that would prevent criminals from entering a bank, but a detective control (security cameras) would record anything they did.
Excerpt from CISA Certified Information Systems Auditor All-In-One Study Guide
Peter H. Gregory 