Expires directive in Nginx - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the Expires header to 1 day.

Nginx

expires [1];

Drag options to blanks, or click blank then click option'

Aoff

B10m

Cmax

D1d

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'off' disables the Expires header.

Using 'max' sets a very long expiration, not 1 day.

Using '10m' sets 10 minutes, not 1 day.

The expires directive with 1d sets the Expires header to 1 day in the future.

2fill in blank

medium

Complete the code to disable the Expires header.

Nginx

expires [1];

Drag options to blanks, or click blank then click option'

Aoff

B1h

C30s

Dmax

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'max' enables very long caching.

Using time values like '1h' or '30s' sets caching durations instead of disabling.

Setting expires off; disables the Expires header, so no caching is done.

3fill in blank

hard

Fix the error in the code to set Expires header to 10 minutes.

Nginx

expires [1];

Drag options to blanks, or click blank then click option'

A10minutes

B10m

C10min

D600s

Attempts:

3 left

💡 Hint

Common Mistakes

Using '10min' or '10minutes' causes syntax errors.

Using seconds like '600s' is valid but less common; '10m' is preferred.

The preferred syntax for 10 minutes is 10m. Forms like 10minutes and 10min are invalid in nginx; 600s is valid but 10m is more common.

4fill in blank

hard

Fill both blanks to set Expires header to 2 hours and disable it for a specific location.

Nginx

location /images/ {
    expires [1];
}
location /nocache/ {
    expires [2];
}

Drag options to blanks, or click blank then click option'

A2h

Boff

C1d

Dmax

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'max' instead of 'off' disables caching incorrectly.

Using '1d' instead of '2h' changes the caching duration.

Setting expires 2h; caches for 2 hours. Setting expires off; disables caching.

5fill in blank

hard

Fill all three blanks to set Expires header with a variable, a time, and disable caching conditionally.

Nginx

set $cache_time [1];
if ($request_uri ~* ".*\.css$") {
    expires [2];
} else {
    expires [3];
}

Drag options to blanks, or click blank then click option'

A1d

Boff

C$cache_time

D10m

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name without setting it first.

Using 'off' for all files disables caching everywhere.

Using a time string directly instead of the variable in the else block.

We set $cache_time to '1d'. CSS files have caching disabled with 'off'. Others use the variable $cache_time.

Practice

1. What is the main purpose of the expires directive in an nginx configuration?

easy

A. To specify the file upload size limit

B. To control how long browsers cache files before requesting them again

C. To limit the number of simultaneous connections

D. To set the server's time zone

Solution

1. Step 1: Understand the role of expires in nginx

   The expires directive tells browsers how long to keep files cached before checking for updates.

2. Step 2: Compare options with this function

   Only To control how long browsers cache files before requesting them again matches this purpose; others relate to different server settings.

3. Final Answer:

   To control how long browsers cache files before requesting them again -> Option B

4. Quick Check:

   Expires directive = browser cache time [OK]

Hint: Expires controls browser cache duration for files [OK]

Common Mistakes:

• Confusing expires with server timezone settings
• Thinking expires limits connections
• Mixing expires with upload size limits

2. Which of the following is the correct syntax to set the expires directive to 1 day in nginx?

easy

A. expires = 1 day;

B. expires 1 day

C. expires 24hours;

D. expires 1d;

Solution

1. Step 1: Recall nginx expires syntax

   The correct syntax uses a time value followed by a semicolon, e.g., expires 1d; for one day.

2. Step 2: Check each option for syntax correctness

   expires = 1 day; uses invalid '=' and full word 'day'; expires 1 day lacks semicolon; expires 24hours; uses invalid time unit '24hours'. Only B matches correct syntax: expires 1d;.

3. Final Answer:

   expires 1d; -> Option D

4. Quick Check:

   Correct syntax ends with semicolon and uses short time unit [OK]

Hint: Use short time units with semicolon, like 'expires 1d;' [OK]

Common Mistakes:

• Omitting semicolon at the end
• Using spaces in time value
• Writing full words like 'day' instead of 'd'

3. Given this nginx config snippet:

location ~* \.(jpg|jpeg|png)$ {
  expires 30d;
}

What will the browser do when accessing a PNG file?

medium

A. Cache the PNG file for 30 seconds

B. Never cache the PNG file

C. Cache the PNG file for 30 days before re-requesting

D. Immediately re-request the PNG file every time

Solution

1. Step 1: Analyze the regex and expires directive

   The location matches .jpg, .jpeg, and .png files and sets expires 30d;, meaning 30 days caching.

2. Step 2: Understand browser caching behavior

   Browsers will keep the PNG file cached for 30 days before checking for updates.

3. Final Answer:

   Cache the PNG file for 30 days before re-requesting -> Option C

4. Quick Check:

   Expires 30d means 30 days cache [OK]

Hint: Regex matches file types; expires sets cache time [OK]

Common Mistakes:

• Confusing days with seconds
• Ignoring regex file matching
• Assuming no caching without explicit 'no-cache'

4. Identify the error in this nginx config:

location /static/ {
  expires 10days;
}

medium

A. The time unit '10days' is invalid; should be '10d'

B. Missing semicolon after expires directive

C. Location block syntax is incorrect

D. Expires directive cannot be used inside location

Solution

1. Step 1: Check the expires time unit

   The correct time unit uses short forms like 'd' for days. '10days' is invalid syntax.

2. Step 2: Verify other syntax elements

   Semicolon is present, location syntax is correct, and expires can be used inside location.

3. Final Answer:

   The time unit '10days' is invalid; should be '10d' -> Option A

4. Quick Check:

   Use short time units like 'd' not full words [OK]

Hint: Use short units like 'd' for days, not full words [OK]

Common Mistakes:

• Writing full words for time units
• Forgetting semicolon (not the case here)
• Thinking expires can't be in location block

5. You want to set caching so that CSS files are cached for 7 days, but HTML files are never cached. Which nginx config snippet achieves this?

hard

A. location ~* \.css$ { expires 7d; } location ~* \.html$ { expires -1; }

B. location ~* \.css$ { expires 7d; } location ~* \.html$ { expires 0; }

C. location ~* \.css$ { expires 7d; } location ~* \.html$ { expires off; }

D. location ~* \.css$ { expires 7d; } location ~* \.html$ { expires never; }

Solution

1. Step 1: Recall how to disable caching in nginx

   Setting expires -1; disables caching (forces no cache) for files.

2. Step 2: Check each option for correct disables and enables

   location ~* \.css$ { expires 7d; } location ~* \.html$ { expires -1; } uses expires 7d; for CSS and expires -1; for HTML, which is correct. Others use invalid or incorrect values.

3. Final Answer:

   location ~* \.css$ { expires 7d; } location ~* \.html$ { expires -1; } -> Option A

4. Quick Check:

   Use 'expires -1;' to disable caching [OK]

Hint: Use 'expires -1;' to disable caching for files [OK]

Common Mistakes:

• Using 'expires off;' which is invalid
• Using 'expires 0;' which sets immediate expiry but not no-cache
• Using 'expires never;' which is not valid syntax