Cache directives describe storage and reuse rules. Public sharing, private caches and revalidation are separate decisions.
Before you start
You should understand clients, servers, IP addresses and ports. Follow a request through name resolution, connection establishment and application exchange. Distinguish protocol guarantees from deployment policy, and use observations from the relevant layer rather than guessing from one browser error message.
The practical goal is to reason through this situation: A personalized response must not accidentally enter a shared cache under a generic key. Read the walkthrough first, then try the interview exercise before opening its answer. The important part is explaining the decision and its consequences, rather than remembering a definition alone.
Step-by-step walkthrough
Step 1: Decide storage sensitivity
Private information may need stricter storage rules than public assets.
Step 2: Separate storage and freshness
No-cache requires validation before reuse; no-store addresses storage.
Step 3: Inspect shared intermediaries
A browser test alone does not establish CDN behavior.
Worked scenario
A personalized response must not accidentally enter a shared cache under a generic key.
A response with no-cache may be retained but must be revalidated according to applicable semantics before reuse. Sensitive account data can need no-store under its policy. Public responses also require a cache key and variation rules that preserve correctness; similarly named directives solve different parts of the problem.
Common mistake
No-cache means revalidate before reuse, not necessarily do not store.
Verify the behavior
Test browser and intermediary reuse, including authenticated responses and changed content.
Interview exercise
Protect sensitive responses.
Answer and reasoning
Choose storage policy from the data’s sensitivity and deployment, and verify intermediary behavior instead of relying on a name’s intuition.
Continue learning
Compare the scenario with the Networking interview questions and test your understanding with the Networking MCQs. For terminology and implementation details, consult the reference material.