Connection configuration in Redis - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

What is the output of this Redis command sequence?

Consider the following Redis commands executed in order:

1. SET user:1:name "Alice"
2. GET user:1:name
3. EXISTS user:1:name
4. DEL user:1:name
5. EXISTS user:1:name

What is the output of the last EXISTS command?

Redis

SET user:1:name "Alice"
GET user:1:name
EXISTS user:1:name
DEL user:1:name
EXISTS user:1:name

A 0

B 1

C nil

D error

💡 Hint

EXISTS returns 1 if the key exists, 0 if it does not.

After deleting the key 'user:1:name', the EXISTS command returns 0 because the key no longer exists.

🧠 Conceptual

intermediate

Which Redis connection option ensures automatic reconnection on connection loss?

You want your Redis client to automatically reconnect if the connection drops. Which connection configuration option should you use?

A password

B retry_strategy

C timeout

D max_clients

💡 Hint

This option defines how the client retries connecting.

The 'retry_strategy' option configures automatic reconnection attempts when the connection is lost.

📝 Syntax

advanced

Which Redis client connection code snippet is syntactically correct for connecting with a password?

Given these four code snippets for connecting to Redis with a password, which one is syntactically correct in Node.js using the 'redis' package?

A const client = redis.createClient({ password: 'mypassword', host: 'localhost', port: 6379 });

B const client = redis.createClient('localhost', 6379, { password: 'mypassword' });

C const client = redis.createClient({ host: 'localhost', port: 6379, auth_pass: 'mypassword' });

D const client = redis.createClient({ url: 'redis://:mypassword@localhost:6379' });

💡 Hint

The modern 'redis' package uses a URL string for connection including password.

Option D uses the correct URL format with password embedded. Other options use deprecated or incorrect syntax.

❓ optimization

advanced

How to optimize Redis connection for high throughput in a Node.js app?

You have a Node.js app that makes many Redis requests. Which connection configuration improves throughput best?

A Set max_clients to 1 to limit connections

B Create a new Redis client for each request

C Use a single shared Redis client instance for all requests

D Disable connection pooling

💡 Hint

Reusing connections reduces overhead.

Using a single shared client avoids overhead of reconnecting and improves throughput.

🔧 Debug

expert

Why does this Redis connection code fail to authenticate?

You run this Node.js code to connect to Redis with a password but get an authentication error:

const client = redis.createClient({ host: 'localhost', port: 6379 });
client.auth('mypassword');
client.connect();

What is the reason for the failure?

Redis

const client = redis.createClient({ host: 'localhost', port: 6379 });
client.auth('mypassword');
client.connect();

A The 'auth' method is deprecated; password must be in connection options or URL

B The port number 6379 is incorrect for password authentication

C The 'connect' method must be called before 'auth'

D Redis does not support password authentication

💡 Hint

Check how the modern Redis client handles authentication.

Modern Redis clients require password in connection options or URL; calling 'auth' separately is deprecated and causes failure.