Which practice enhances REST response cacheability?

• A. Always private responses that cannot be cached.
• B. Disable all caching to prevent stale data.
• C. Use standard HTTP cache-control headers to guide caching behavior.
• D. Use custom non-standard headers only.

Answer: (C)

Caching in REST hinges on standard HTTP rules. Caches like browsers, proxies, and CDNs rely on HTTP headers to decide if a response can be stored, for how long, and when it should be revalidated. By using standard headers such as Cache-Control with directives like public, private, and max-age, along with validators like ETag and Last-Modified, you give caches clear, interoperable instructions about freshness and revalidation. This makes caching decisions predictable across different caches, boosting performance and reducing load while maintaining correctness when resources change.

Other approaches fall short: making every response private prevents caching, while disabling all caching eliminates its benefits. Relying on custom non-standard headers won’t be understood by caches, so they can’t apply proper caching rules.