Next.js · Caching · Fresh / Intern · Concept
What caching layers exist in Next.js App Router?
Short Interview Answer
Request memoization, Data Cache, Full Route Cache, and Router Cache (client).
Detailed Explanation
Each layer has different lifetimes and invalidation. Interviews often probe whether you can name and distinguish them. Misconfiguring one causes 'why is this stale?' bugs.
Interview Tip
Name the four caches clearly.