Redis configuration file - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the Redis server port to 6379.

Redis

port [1]

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

A6379

B6380

C7000

D8080

Attempts:

3 left

💡 Hint

Common Mistakes

Using a port number that is not standard for Redis.

Leaving the port number blank or commented out.

The default Redis port is 6379. Setting port 6379 configures Redis to listen on this port.

2fill in blank

medium

Complete the code to enable Redis persistence with RDB snapshots every 900 seconds if at least 1 key changed.

Redis

save [1] 1

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

A300

B1800

C60

D900

Attempts:

3 left

💡 Hint

Common Mistakes

Using too short or too long intervals that do not match the requirement.

Confusing the order of parameters in the save directive.

The save 900 1 directive tells Redis to save the DB if at least 1 key changed in 900 seconds.

3fill in blank

hard

Fix the error in the line to disable protected mode in Redis configuration.

Redis

protected-mode [1]

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

Atrue

Byes

Cno

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'true' or 'false' instead of 'yes' or 'no'.

Leaving protected mode enabled when it should be disabled.

To disable protected mode, set protected-mode no. Using 'yes' or boolean strings causes errors.

4fill in blank

hard

Fill both blanks to configure Redis to require a password and set it to 'mypassword'.

Redis

requirepass [1]
# Uncomment to enable password
# requirepass [2]

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

Amypassword

Bpassword123

Credispass

Dsecret

Attempts:

3 left

💡 Hint

Common Mistakes

Using different passwords in the two places.

Leaving the password commented out.

The requirepass directive sets the password Redis requires for clients. Both blanks must be the same password.

5fill in blank

hard

Fill all three blanks to configure Redis to bind only to localhost, disable protected mode, and set maxmemory to 256mb.

Redis

bind [1]
protected-mode [2]
maxmemory [3]

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

A127.0.0.1

Bno

C256mb

D0.0.0.0

Attempts:

3 left

💡 Hint

Common Mistakes

Binding to 0.0.0.0 exposes Redis to all interfaces.

Using 'yes' instead of 'no' for protected mode.

Setting maxmemory without units.

Binding to 127.0.0.1 restricts Redis to localhost. Disabling protected mode requires 'no'. Setting maxmemory to '256mb' limits memory usage.

Practice

1. What is the main purpose of the Redis configuration file?

easy

A. To write Redis commands

B. To store user data permanently

C. To display Redis logs

D. To control how Redis runs and behaves

Solution

1. Step 1: Understand the role of configuration files

   Configuration files set options that control how software behaves.

2. Step 2: Apply this to Redis

   The Redis configuration file sets how Redis runs, including memory use and security.

3. Final Answer:

   To control how Redis runs and behaves -> Option D

4. Quick Check:

   Redis config file = controls Redis behavior [OK]

Hint: Config files set behavior, not data or commands [OK]

Common Mistakes:

• Thinking config stores data
• Confusing config with command input
• Assuming config shows logs

2. Which line is the correct syntax to set the Redis port to 6380 in the configuration file?

easy

A. set port=6380

B. port 6380

C. port: 6380

D. port=6380

Solution

1. Step 1: Recall Redis config syntax

   Redis config uses simple lines: setting_name followed by value, separated by space.

2. Step 2: Check each option

   port 6380 matches this syntax: 'port 6380'. Others use invalid symbols or keywords.

3. Final Answer:

   port 6380 -> Option B

4. Quick Check:

   Redis config syntax = setting value [OK]

Hint: Use space between setting and value, no equals or colons [OK]

Common Mistakes:

• Using '=' instead of space
• Adding 'set' keyword
• Using colon ':' instead of space

3. Given this Redis config snippet:

save 900 1
save 300 10
save 60 10000
port 6379
maxmemory 256mb

What does the save 300 10 line mean?

medium

A. Save the DB if at least 10 keys changed in 300 seconds

B. Save the DB every 300 seconds regardless of changes

C. Save the DB if 300 keys changed in 10 seconds

D. Save the DB only once after 300 seconds

Solution

1. Step 1: Understand Redis save syntax

   The 'save' command uses two numbers: seconds and number of changes to trigger saving.

2. Step 2: Interpret 'save 300 10'

   This means: if 10 or more keys changed in 300 seconds, Redis saves the DB.

3. Final Answer:

   Save the DB if at least 10 keys changed in 300 seconds -> Option A

4. Quick Check:

   save seconds changes = save if changes in seconds [OK]

Hint: First number = seconds, second = changes to trigger save [OK]

Common Mistakes:

• Mixing order of seconds and changes
• Thinking save triggers every fixed time
• Ignoring the number of changes

4. You added this line to your Redis config file:
maxmemory 512mb
But Redis still uses more memory than 512MB. What is the likely problem?

medium

A. Redis needs to be restarted to apply config changes

B. The maxmemory setting requires a unit in uppercase (MB), not lowercase

C. maxmemory only limits disk usage, not RAM

D. The config file must have 'set maxmemory 512mb'

Solution

1. Step 1: Check Redis config behavior

   Redis reads config file only at startup or when reloaded.

2. Step 2: Understand applying changes

   Changing config file alone does not affect running Redis until restart or reload.

3. Final Answer:

   Redis needs to be restarted to apply config changes -> Option A

4. Quick Check:

   Config changes require restart or reload [OK]

Hint: Restart Redis after config edits to apply changes [OK]

Common Mistakes:

• Assuming lowercase units are invalid
• Thinking maxmemory limits disk space
• Using 'set' keyword in config file

5. You want Redis to save data only if at least 5 keys change within 600 seconds, and limit memory to 1GB. Which two lines should you add to the config file?

hard

A. save 600 5
maxmemory 1mb

B. save 5 600
maxmemory 1024mb

C. save 600 5
maxmemory 1024mb

D. save 5 600
maxmemory 1gb

Solution

1. Step 1: Write correct save syntax

   Save syntax is 'save <seconds> <changes>', so 'save 600 5' means save if 5 keys change in 600 seconds.

2. Step 2: Write correct maxmemory value

   For 1GB (1024MB), 'maxmemory 1024mb' is correct (A). C uses '1mb' (only 1MB, too small).

3. Step 3: Choose correct combined lines

   save 600 5 maxmemory 1024mb uses correct save syntax and valid maxmemory value.

4. Final Answer:

   save 600 5 maxmemory 1024mb -> Option C

5. Quick Check:

   save seconds changes + maxmemory in mb or gb [OK]

Hint: Save uses seconds then changes; maxmemory accepts mb or gb [OK]

Common Mistakes:

• Swapping seconds and changes in save
• Using invalid memory units
• Mixing order of lines