Cache-Control headers in Nginx - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the effect of this Cache-Control header in nginx?

Given this nginx configuration snippet, what Cache-Control header will be sent to clients?

location /images/ {
  add_header Cache-Control "public, max-age=86400";
}

Nginx

curl -I http://example.com/images/logo.png

A Cache-Control: public, max-age=86400

B Cache-Control: no-cache

C Cache-Control: private, max-age=86400

D Cache-Control: no-store

💡 Hint

Look at the add_header directive and the value it sets.

The add_header directive sets the Cache-Control header exactly as specified. Here it sets it to 'public, max-age=86400', meaning the response can be cached by any cache for 86400 seconds (1 day).

🧠 Conceptual

intermediate

Which Cache-Control directive prevents caching by browsers but allows caching by proxies?

Select the Cache-Control directive that stops browsers from caching but still allows intermediate proxies to cache the response.

A no-store

B private

C public

D no-cache

💡 Hint

Think about which directive requires revalidation but does not forbid caching.

The 'no-cache' directive means caches must revalidate with the server before using the cached copy. Browsers will revalidate, effectively preventing stale content, but proxies can still cache it. 'private' restricts caching to browsers only, 'no-store' forbids caching entirely, and 'public' allows caching everywhere.

❓ Configuration

advanced

How to configure nginx to disable caching for all HTML files?

Choose the correct nginx configuration snippet that disables caching for all .html files by setting Cache-Control headers.

A

location ~* \.html$ {
  add_header Cache-Control "public, max-age=3600";
}

B

location ~* \.html$ {
  add_header Cache-Control "no-store, no-cache, must-revalidate, proxy-revalidate, max-age=0";
}

C

location ~* \.html$ {
  add_header Cache-Control "private, max-age=86400";
}

D

location ~* \.html$ {
  add_header Cache-Control "max-age=31536000";
}

💡 Hint

Disabling caching means telling browsers and proxies not to store the response.

The configuration in option B sets Cache-Control headers that instruct browsers and proxies not to cache the HTML files by using 'no-store' and 'no-cache' along with revalidation directives and max-age=0. Other options allow caching.

❓ Troubleshoot

advanced

Why is nginx not sending Cache-Control headers despite add_header directive?

You added 'add_header Cache-Control "max-age=3600";' inside a location block, but curl responses do not show Cache-Control headers. What is the most likely reason?

A Cache-Control headers are overridden by browser settings

B The syntax of add_header is incorrect and causes it to be ignored

C The add_header directive is ignored for 4xx and 5xx responses by default

D nginx does not support Cache-Control headers

💡 Hint

Check nginx behavior for error responses and add_header.

By default, nginx only adds headers with add_header on successful (2xx) responses. For error responses (4xx, 5xx), add_header is ignored unless you use 'always' parameter. So if the response is an error, Cache-Control won't be sent.

🔀 Workflow

expert

Order the steps to implement and verify Cache-Control headers in nginx

Put these steps in the correct order to add Cache-Control headers and verify they work.

A 1,2,3,4

B 2,1,3,4

C 1,3,2,4

D 3,1,2,4

💡 Hint

Think about editing config, applying it, then testing.

First edit the config, then reload nginx to apply changes, then test with curl, and finally confirm the header is correct.