Redis configuration file - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

What is the output of this Redis command?

Given the Redis configuration file has maxmemory 100mb set, what will the command CONFIG GET maxmemory return?

Redis

CONFIG GET maxmemory

A ["maxmemory", "104857600"]

B ["maxmemory", "100mb"]

C ["maxmemory", "100"]

D ["maxmemory", "100000000"]

💡 Hint

Redis stores memory sizes in bytes internally.

The maxmemory value is returned in bytes. 100mb equals 100 * 1024 * 1024 = 104857600 bytes.

📝 Syntax

intermediate

Identify the syntax error in this Redis config line

Which option shows a syntax error in Redis configuration file for setting the port?

A port=6379

B port 6379

C port 0

D port 6380

💡 Hint

Redis config lines use space, not equal sign.

Redis configuration lines use space to separate directive and value. Using '=' causes syntax error.

❓ optimization

advanced

Which configuration optimizes Redis persistence for minimal data loss?

To minimize data loss in Redis, which configuration setting is best?

A save "900 1"

B appendfsync no

C appendfsync everysec

D appendonly yes

💡 Hint

Consider how often Redis writes data to disk.

Setting 'appendfsync everysec' makes Redis sync the append-only file every second, balancing performance and data safety.

🔧 Debug

advanced

Why does Redis fail to start with this config line?

Given the config line maxclients -100, why does Redis fail to start?

Redis

maxclients -100

A maxclients must be a string, not a number

B maxclients cannot be set in config file

C maxclients must be zero or positive

D Negative maxclients value is invalid

💡 Hint

Check allowed value ranges for maxclients.

maxclients must be a positive integer; negative values cause startup failure.

🧠 Conceptual

expert

What is the effect of setting protected-mode no in Redis config?

Choose the correct effect of protected-mode no in Redis configuration.

A Enables password authentication for all clients

B Disables security protections, allowing external connections without authentication

C Limits Redis to accept connections only from localhost

D Enables encryption for all Redis traffic

💡 Hint

Protected mode is a safety feature for Redis servers exposed to networks.

Setting protected-mode to no disables the default safety feature that blocks external connections without authentication.