89 original practice questions across 9 topics, every answer explained. Study mode shows the reasoning as you go; test mode holds it until the end.
89 questions
Which file makes a route segment publicly accessible in the App Router?
What is the default rendering environment for a component in the app/ directory?
What does layout.tsx do that template.tsx does not?
Which special file renders while a route segment's data is loading?
What does error.tsx require that other special files do not?
Which errors does error.tsx NOT catch?
What is a route group, written as a folder in parentheses like (marketing)?
What does a folder prefixed with an underscore, like _components, do?
How do you define a dynamic route segment?
In Next.js 15 and later, what type is the params prop passed to a page?
What is the difference between [...slug] and [[...slug]]?
What are parallel routes, defined with the @folder convention?
What are intercepting routes, written with (.) or (..) prefixes?
What does not-found.tsx render?
Which component should you use for client-side navigation between routes?
What does the 'use client' directive actually do?
Can a Server Component import and render a Client Component?
How do you render a Server Component inside a Client Component?
Which of these can a Server Component NOT do?
What happens if you use onClick on a Server Component?
Which values can be passed as props from a Server Component to a Client Component?
Where should you place 'use client' to minimize bundle size?
What does the server-only package do?
Can a Client Component be async?
What is the practical bundle-size effect of a Server Component?
Which hooks are available in Client Components but not Server Components?
What does cookies() from next/headers return in Next.js 15+?
What is the 'use server' directive used for?
Why does a Client Component still appear in the initial HTML source?
How do you skip server-rendering for a component that needs window?
In Next.js 15 and later, are fetch() requests cached by default?
What does fetch(url, { next: { revalidate: 3600 } }) do?
What does fetch(url, { next: { tags: ['posts'] } }) enable?
What is request memoization in the App Router?
What does the 'use cache' directive introduced in Next.js 16 do?
What are Cache Components in Next.js 16?
What is Partial Prerendering (PPR)?
What does unstable_cache wrap?
What makes a route dynamic rather than static?
What does export const dynamic = 'force-dynamic' do?
What does generateStaticParams do?
What happens to a dynamic route not covered by generateStaticParams when dynamicParams is false?
What is the correct way to fetch two independent datasets without waterfalling?
How do you stream a slow section of a page without blocking the rest?
What does revalidatePath('/blog') do?
Where should you call revalidatePath or revalidateTag?
In Next.js 15+, are GET Route Handlers cached by default?
What is the Client Router Cache?
Which rendering strategy generates HTML at build time and serves the same output to every user?
What does Incremental Static Regeneration add to SSG?
During ISR revalidation, what does a user see?
What is the main trade-off of server-side rendering on every request?
What is streaming SSR?
Which Core Web Vital does streaming most directly improve?
What is hydration in the Next.js context?
What commonly causes a hydration mismatch error?
Does Next.js support client-side-only rendering for a whole route?
What does export const revalidate = 60 at the page level mean?
What file defines an API endpoint in the App Router?
Can route.ts and page.tsx exist in the same folder?
What replaced middleware.ts in Next.js 16?
What is the correct use of the proxy/middleware layer?
How do you limit which paths the proxy runs on?
What does NextResponse.rewrite() do differently from NextResponse.redirect()?
How do you read the request body in a POST Route Handler?
How do you set a custom status code in a Route Handler?
Which runtime does a Route Handler use by default?
What is a Server Action?
How do you attach a Server Action to a form?
What does useFormStatus provide?
What does useActionState return?
Must Server Actions validate their input?
Can a Server Action be defined inside a Client Component file?
What does redirect() do inside a Server Action?
What does next/form add over a plain <form>?
How do you set a page title in the App Router?
What does a title.template in a layout's metadata do?
Which file convention generates a sitemap?
How do you generate dynamic Open Graph images?
What does the alternates.canonical metadata field control?
Why does structured data (JSON-LD) matter for a quiz or FAQ page?
What does next/image do that a plain <img> does not?
When should you set the priority prop on next/image?
Why must remote image domains be configured in next.config?
What problem does next/font solve?
What does the strategy prop on next/script control?
What does next/dynamic primarily achieve?
Which tool identifies what is inflating your bundle?
What is the default bundler in Next.js 16?