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Next.js / ASP.NET Core / SQL6 min study
12/ 41

The edge

CDNs and edge caching

Serving static files from the point nearest the user, and knowing what must never be cached.

UnderstandStudy an examplePractise

Understand the concept

A CDN (Content Delivery Network) consists of servers spread around the world. When a user requests a file, the nearest edge responds; if it lacks the file it fetches it from the origin and stores it for later requests. Shorter distance means less latency and less load on the origin.

The Cache-Control header decides how long things are kept. Next.js build output for JavaScript and CSS includes a content hash in the file name; when content changes, the name changes. Those files can therefore be cached for a year as ‘immutable’. HTML may vary per user and must stay fresh, so it is usually cached briefly or not at all.

The most dangerous mistake is putting a personal response into a shared cache. ‘private’ means only the browser may store it; ‘no-store’ means nobody may. Caching a page that depends on a session cookie as ‘public’ can show one user’s data to others.

WHEN TO USE IT

Correct cache headers decide both speed and data privacy.

COMMON PITFALL

Sending a session-dependent response with Cache-Control: public.

01 / PRACTICE

One topic. Three levels of depth.

Illustrative example
/_next/static/chunks/main-3f9a1c.js
Cache-Control: public, max-age=31536000, immutable

A file whose name changes with its content can be cached for a year.

This page connects to no real server or database. Code samples are illustrative for .NET 8, Next.js and SQL Server; timings are example values in the simulation, not measurements. Try samples only in your own development environment; never share real connection strings, tokens or passwords.

02 / YOUR TURN

Try it yourself first.

You fixed a CSS file but users keep seeing the old look. It is served as ‘/styles.css’ with max-age=31536000. What is the problem and the fix?

Show the solution and explanation
Worked solution
Ad değişmediği için tarayıcı ve CDN bir yıl boyunca eski dosyayı kullanır.
Çözüm: dosya adına içerik özeti eklemek (styles.3f9a1c.css)
veya bu adı kısa max-age ile sunmak.

Long-lived caching is only safe for files whose name changes when their content does.