REPLICAOF command in Redis - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to make the current Redis server a replica of another server at IP 192.168.1.10 and port 6379.

Redis

REPLICAOF [1] 6379

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

Alocalhost

B192.168.1.10

C127.0.0.1

D0.0.0.0

Attempts:

3 left

💡 Hint

Common Mistakes

Using localhost instead of the actual IP address.

Using the wrong port number.

The REPLICAOF command requires the IP address of the master server. Here, 192.168.1.10 is the correct IP.

2fill in blank

medium

Complete the command to stop replication and make the Redis server a master again.

Redis

REPLICAOF [1] [2]

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

ANO

BONE

CNONE

D0 0

Attempts:

3 left

💡 Hint

Common Mistakes

Using REPLICAOF NONE 0 0 which is invalid.

Using only one argument after REPLICAOF.

To stop replication, use REPLICAOF NO ONE.

3fill in blank

hard

Fix the error in the command to replicate from master at IP 10.0.0.5 and port 6380.

Redis

REPLICAOF [1] 6380

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

A10.0.0.5

B10.0.0.5:6380

Clocalhost

D6380

Attempts:

3 left

💡 Hint

Common Mistakes

Combining IP and port with a colon.

Using the port number as the IP argument.

The REPLICAOF command requires the IP address and port as separate arguments. Using '10.0.0.5:6380' is invalid syntax.

4fill in blank

hard

Fill both blanks to replicate from master at IP 172.16.0.2 and port 7000.

Redis

REPLICAOF [1] [2]

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

A172.16.0.2

B7000

C6379

Dlocalhost

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping IP and port arguments.

Using default port 6379 instead of 7000.

The first blank is the master's IP address, the second blank is the master's port number.

5fill in blank

hard

Fill all four blanks to replicate from master at IP 192.168.100.50, port 6381, and then stop replication.

Redis

REPLICAOF [1] [2]
REPLICAOF [3] [4]

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

A192.168.100.50

B6381

CNO

DONE

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong IP or port in first command.

Incorrect syntax to stop replication.

First command sets replication to the master IP and port. Second command stops replication by using NO ONE.

Practice

1. What does the REPLICAOF command do in Redis?

easy

A. It resets the Redis server to factory settings.

B. It deletes all data from the Redis server.

C. It creates a backup file of the Redis database.

D. It makes the Redis server copy data from another Redis server.

Solution

1. Step 1: Understand the purpose of REPLICAOF

   The REPLICAOF command is used to set a Redis server as a replica, meaning it copies data from a master server.

2. Step 2: Compare options with the command's function

   Only It makes the Redis server copy data from another Redis server. correctly describes this behavior. Other options describe unrelated actions.

3. Final Answer:

   It makes the Redis server copy data from another Redis server. -> Option D

4. Quick Check:

   REPLICAOF copies data = A [OK]

Hint: REPLICAOF means 'copy from another server' [OK]

Common Mistakes:

• Confusing REPLICAOF with backup commands
• Thinking it deletes data
• Assuming it resets server settings

2. Which of the following is the correct syntax to stop replication and make a Redis server standalone?

easy

A. REPLICAOF NO ONE

B. REPLICAOF NONE

C. REPLICAOF STOP

D. REPLICAOF DISABLE

Solution

1. Step 1: Recall the exact syntax to stop replication

   The correct command to stop replication is REPLICAOF NO ONE.

2. Step 2: Verify other options

   Options A, B, and D are invalid Redis commands for stopping replication.

3. Final Answer:

   REPLICAOF NO ONE -> Option A

4. Quick Check:

   Stop replication = REPLICAOF NO ONE [OK]

Hint: Use 'NO ONE' exactly to stop replication [OK]

Common Mistakes:

• Using 'NONE' instead of 'NO ONE'
• Trying 'STOP' or 'DISABLE' which are invalid
• Missing the space between REPLICAOF and NO ONE

3. If you run REPLICAOF 192.168.1.10 6379 on a Redis server, what will happen?

medium

A. The server will become a replica and copy data from the server at 192.168.1.10 port 6379.

B. The server will delete all data and stop working.

C. The server will create a backup of the server at 192.168.1.10.

D. The server will reject the command with a syntax error.

Solution

1. Step 1: Understand the REPLICAOF command with IP and port

   Running REPLICAOF 192.168.1.10 6379 sets the server as a replica of the specified IP and port.

2. Step 2: Check other options for correctness

   Options B and C describe unrelated actions. The server will reject the command with a syntax error. is incorrect because the syntax is valid.

3. Final Answer:

   The server will become a replica and copy data from the server at 192.168.1.10 port 6379. -> Option A

4. Quick Check:

   REPLICAOF IP PORT = replica mode [OK]

Hint: IP and port after REPLICAOF set replica source [OK]

Common Mistakes:

• Thinking it deletes data
• Assuming it creates backups
• Believing the syntax is invalid

4. You tried to run REPLICAOF NOONE to stop replication, but it failed. What is the error?

medium

A. The command should be REPLICAOF NONE instead.

B. You need to restart the Redis server before stopping replication.

C. The command is missing a space; it should be REPLICAOF NO ONE.

D. The command is correct; the failure is due to network issues.

Solution

1. Step 1: Identify the syntax error in the command

   The command REPLICAOF NOONE is invalid because it lacks a space between NO and ONE.

2. Step 2: Confirm the correct syntax

   The correct command is REPLICAOF NO ONE. Other options are incorrect because they suggest wrong commands or unrelated issues.

3. Final Answer:

   The command is missing a space; it should be REPLICAOF NO ONE. -> Option C

4. Quick Check:

   Correct stop syntax = REPLICAOF NO ONE [OK]

Hint: Remember space between NO and ONE to stop replication [OK]

Common Mistakes:

• Writing NOONE as one word
• Using NONE instead of NO ONE
• Assuming restart is needed to stop replication

5. You want to set up a Redis replica for backup but also want to stop replication temporarily without losing data. Which sequence of commands should you use?

hard

A. Run REPLICAOF NO ONE first, then REPLICAOF 192.168.1.20 6379 to start replication.

B. First run REPLICAOF 192.168.1.20 6379 to start replication, then REPLICAOF NO ONE to stop it temporarily.

C. Run REPLICAOF STOP to pause replication, then REPLICAOF START to resume.

D. Use REPLICAOF DISABLE to stop replication and REPLICAOF ENABLE to start it again.

Solution

1. Step 1: Understand how to start replication

   Use REPLICAOF IP PORT to start replication from a master server.

2. Step 2: Understand how to stop replication temporarily

   Use REPLICAOF NO ONE to stop replication without deleting data or resetting the server.

3. Step 3: Evaluate options

   First run REPLICAOF 192.168.1.20 6379 to start replication, then REPLICAOF NO ONE to stop it temporarily. correctly shows starting replication then stopping it temporarily. Options C and D use invalid commands. Run REPLICAOF NO ONE first, then REPLICAOF 192.168.1.20 6379 to start replication. reverses the order, which is less logical for setup.

4. Final Answer:

   First run REPLICAOF 192.168.1.20 6379 to start replication, then REPLICAOF NO ONE to stop it temporarily. -> Option B

5. Quick Check:

   Start with IP, stop with NO ONE [OK]

Hint: Start replica with IP, stop with NO ONE command [OK]

Common Mistakes:

• Using invalid commands like STOP or DISABLE
• Stopping replication before starting it
• Thinking stopping deletes data