Open file cache in Nginx - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to enable open file cache in nginx.

Nginx

open_file_cache [1];

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

Aoff

Bon

Cenable

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'enable' or 'true' instead of 'on'.

Leaving the directive off or empty.

The open_file_cache directive is enabled by setting it to on.

2fill in blank

medium

Complete the code to set the maximum number of cached files.

Nginx

open_file_cache max=[1];

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

A100

B5000

C1000

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Setting the value too low like 10, which limits caching.

Setting an excessively high value like 5000 without need.

The open_file_cache max directive sets the maximum number of cached files. A typical value is 100.

3fill in blank

hard

Fix the error in the open file cache timeout setting.

Nginx

open_file_cache_valid [1];

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

A30sec

B30

C30seconds

D30s

Attempts:

3 left

💡 Hint

Common Mistakes

Using just a number without units.

Using incorrect unit words like 'sec' or 'seconds'.

The open_file_cache_valid directive requires a time value with units, like 30s for 30 seconds.

4fill in blank

hard

Fill both blanks to configure open file cache with max files and inactive timeout.

Nginx

open_file_cache [1] inactive=[2];

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

Amax=200

B10m

Cmax=100

D5m

Attempts:

3 left

💡 Hint

Common Mistakes

Using just numbers without 'max=' for max files.

Using invalid time units for inactive timeout.

Use max=100 to set max cached files and 10m for 10 minutes inactive timeout.

5fill in blank

hard

Fill all three blanks to complete the open file cache configuration with max files, inactive timeout, and min uses.

Nginx

open_file_cache [1] inactive=[2];
open_file_cache_min_uses [3];

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

Amax=150

B15m

C2

Dmax=50

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing min uses with timeout values.

Omitting 'max=' prefix for max files.

Using invalid time units.

Set max cached files with max=150, inactive timeout to 15m, and minimum uses to 2.

Practice

1. What is the main purpose of the open_file_cache directive in nginx?

easy

A. To limit the number of open connections to clients

B. To store file information in memory to speed up file access

C. To cache HTTP responses from upstream servers

D. To compress files before sending them to clients

Solution

1. Step 1: Understand the role of open_file_cache

   The open_file_cache directive caches file metadata like file descriptors and attributes.

2. Step 2: Identify its effect on performance

   By caching file info, nginx reduces disk access and speeds up serving static files.

3. Final Answer:

   To store file information in memory to speed up file access -> Option B

4. Quick Check:

   open_file_cache purpose = cache file info [OK]

Hint: Remember: open_file_cache speeds file access by caching file info [OK]

Common Mistakes:

• Confusing open_file_cache with HTTP response caching
• Thinking it limits client connections
• Assuming it compresses files

2. Which of the following is the correct syntax to enable open file cache with 1000 max cached files and 60 seconds inactive timeout?

easy

A. open_file_cache max=1000 inactive=60;

B. open_file_cache 1000 60s;

C. open_file_cache max=1000 inactive=60s;

D. open_file_cache max=1000 inactive=60sec;

Solution

1. Step 1: Recall correct open_file_cache syntax

   The syntax requires named parameters like max= and inactive= with time units.

2. Step 2: Check each option for correctness

   open_file_cache max=1000 inactive=60s; uses correct parameter names and time unit s for seconds.

3. Final Answer:

   open_file_cache max=1000 inactive=60s; -> Option C

4. Quick Check:

   Use named params with units for open_file_cache [OK]

Hint: Use named parameters with units like 'inactive=60s' [OK]

Common Mistakes:

• Omitting parameter names
• Missing time units for inactive
• Using incorrect time unit abbreviations

3. Given this nginx config snippet:

open_file_cache max=2 inactive=30s;
open_file_cache_valid 10s;

What happens when nginx tries to serve 3 different files within 10 seconds?

medium

A. All 3 files are cached because open_file_cache_valid is 10s

B. All files are cached but expire after 30 seconds

C. No files are cached because max is less than 3

D. Only 2 files are cached; the third file info is not cached

Solution

1. Step 1: Understand max parameter effect

   The max=2 limits cache to 2 file entries only.

2. Step 2: Analyze caching of 3 files

   When 3 files are requested, only 2 can be cached; the third is not cached.

3. Final Answer:

   Only 2 files are cached; the third file info is not cached -> Option D

4. Quick Check:

   max=2 limits cache size to 2 files [OK]

Hint: max limits cached files count; extras are not cached [OK]

Common Mistakes:

• Assuming all files cache regardless of max
• Confusing open_file_cache_valid with max
• Thinking inactive controls cache size

4. You configured open_file_cache max=100 inactive=60s; but notice no caching effect. What is a likely cause?

medium

A. You forgot to enable open_file_cache_valid directive

B. The max value is too high to cache files

C. The inactive time is too short to cache files

D. open_file_cache only works with dynamic content

Solution

1. Step 1: Check required directives for caching

   Besides open_file_cache, open_file_cache_valid must be set to define cache validity.

2. Step 2: Identify missing directive effect

   Without open_file_cache_valid, cached entries expire immediately, so no caching effect.

3. Final Answer:

   You forgot to enable open_file_cache_valid directive -> Option A

4. Quick Check:

   open_file_cache_valid enables cache duration [OK]

Hint: Always set open_file_cache_valid to activate caching [OK]

Common Mistakes:

• Ignoring open_file_cache_valid directive
• Misunderstanding max and inactive roles
• Thinking open_file_cache works only for dynamic content

5. You want to optimize nginx for a high-traffic static site. Which open_file_cache settings best improve performance while avoiding stale data?

hard

A. open_file_cache max=1000 inactive=60s; open_file_cache_valid 30s;

B. open_file_cache max=10 inactive=300s; open_file_cache_valid 300s;

C. open_file_cache max=5000 inactive=5s; open_file_cache_valid 1s;

D. open_file_cache max=100 inactive=3600s; open_file_cache_valid 3600s;

Solution

1. Step 1: Balance cache size and freshness

   High-traffic static sites benefit from a large cache (max=1000) and moderate inactive timeout (60s) to keep data fresh.

2. Step 2: Set cache validity to avoid stale data

   open_file_cache_valid 30s ensures cached info refreshes often enough to prevent stale data.

3. Final Answer:

   open_file_cache max=1000 inactive=60s; open_file_cache_valid 30s; -> Option A

4. Quick Check:

   Large max + moderate inactive + short valid = best performance [OK]

Hint: Use large max, moderate inactive, short valid for fresh cache [OK]

Common Mistakes:

• Setting max too low for traffic
• Using too long inactive or valid causing stale cache
• Setting valid too short causing overhead