Q: What is the Data Cache in Next.js and how do you opt out of it?

The **Data Cache** stores fetch (and cached function) results on the **server across requests and deployments** to avoid refetching. Opt out per fetch with cache: 'no-store' , per segment with export const dynamic = 'force-dynamic' or revalidate = 0 — so data is always fresh. <rect class='d-box-accent' x='2

Question 1

What happens when you run next dev, next build and next start?

Accepted Answer

**Target Audience:** Beginners preparing for Next.js interviews — no prior Next.js knowledge assumed.
**Difficulty:** Easy

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:`. Every behaviour claim was checked against the Next.js 16.4.2 docs shipped with the package and, in the **Verified** section, against a real `create-next-app@16.4.2` project run under all three commands and probed with `curl`.

## 1. Why This Even Matters — A St

Question 2

What is Draft Mode in Next.js and how does it work with a headless CMS?

Accepted Answer

**Target Audience:** Frontend engineers preparing for Next.js interviews — assumes basic React and App Router familiarity.
**Difficulty:** Medium

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:`. Every behaviour claim was checked against the Next.js 16.4.2 docs shipped with the package and, in the **Verified** section, against real output from a build, a running server or a real Chromium browser. **No real CMS was used:** the lab

Question 3

What is the Data Cache in Next.js and how do you opt out of it?

Accepted Answer

The **Data Cache** stores fetch (and cached function) results on the **server across requests and deployments** to avoid refetching. Opt out per fetch with cache: 'no-store', per segment with export const dynamic = 'force-dynamic' or revalidate = 0 — so data is always fresh.

Question 4

What makes a route dynamic in the Next.js App Router?

Accepted Answer

**Target Audience:** Frontend engineers preparing for Next.js interviews — assumes basic React and App Router familiarity.
**Difficulty:** Medium

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:`. Every behaviour claim was checked against the Next.js docs shipped with the package (written on 16.3.4, re-reviewed against 16.4.2) and, in the **Verified** section, against real output from a build or a running server; each Verified bloc

Question 5

How does fetch caching work in the Next.js App Router (force-cache, no-store, revalidate)?

Accepted Answer

**Target Audience:** Frontend engineers preparing for Next.js interviews — assumes basic React and App Router familiarity.
**Difficulty:** Medium

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:`. Every behaviour claim was checked against the Next.js docs shipped with the package (written on 16.3.4, re-reviewed against 16.4.2) and, in the **Verified** section, against real output from a build or a running server; each Verified bloc

Question 6

What is request memoization in Next.js?

Accepted Answer

**Target Audience:** Frontend engineers preparing for Next.js interviews — assumes basic React and App Router familiarity.
**Difficulty:** Medium

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:`. Every behaviour claim was checked against the Next.js docs shipped with the package (written on 16.3.4, re-reviewed against 16.4.2) and, in the **Verified** section, against real output from a build or a running server; each Verified bloc

Question 7

What is the Full Route Cache in Next.js?

Accepted Answer

**Target Audience:** Frontend engineers preparing for Next.js interviews — assumes basic React and App Router familiarity.
**Difficulty:** Hard

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:`. Every behaviour claim was checked against the Next.js docs shipped with the package (written on 16.3.4, re-reviewed against 16.4.2) and, in the **Verified** section, against real output from a build or a running server; each Verified block

NEXT.JSDECODED.

Easy

What happens when you run next dev, next build and next start?

Medium

What is Draft Mode in Next.js and how does it work with a headless CMS?

What is the Data Cache in Next.js and how do you opt out of it?

What makes a route dynamic in the Next.js App Router?

How does fetch caching work in the Next.js App Router (force-cache, no-store, revalidate)?

What is request memoization in Next.js?

Hard

What is the Full Route Cache in Next.js?