Failover manual process in Redis - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Redis manual failover steps

Which of the following sequences correctly describes the manual failover process in Redis Sentinel?

A Promote the slave to master, update clients, and then notify Sentinel.

B Promote the slave to master, notify Sentinel, then update clients.

C Notify Sentinel, promote the slave to master, then update clients.

D Update clients, notify Sentinel, then promote the slave to master.

💡 Hint

Think about the order: first change the role, then inform the system, then clients.

In manual failover, you first promote the slave to master, then notify Sentinel so it updates its state, and finally update clients to connect to the new master.

❓ query_result

intermediate

Result of manual failover command in Redis CLI

What is the expected output after running SLAVEOF NO ONE on a Redis slave during manual failover?

Redis

SLAVEOF NO ONE

A +OK

B -ERR unknown command 'SLAVEOF NO ONE'

C +FAILOVER_STARTED

D -ERR wrong number of arguments for 'SLAVEOF' command

💡 Hint

Consider the standard Redis response for successful commands.

The SLAVEOF NO ONE command successfully promotes the slave to master and returns +OK.

📝 Syntax

advanced

Identify the correct Redis CLI command for manual failover

Which of the following Redis CLI commands correctly initiates manual failover by promoting a slave to master?

A SLAVEOF NO ONE

B FAILOVER PROMOTE

C MASTER PROMOTE

D SENTINEL FAILOVER

💡 Hint

Remember the exact Redis command to stop replication and become master.

SLAVEOF NO ONE is the correct command to promote a slave to master manually.

🔧 Debug

advanced

Troubleshooting manual failover: why clients still connect to old master?

After manually promoting a slave to master, clients still connect to the old master. What is the most likely cause?

A Sentinel automatically reverted the failover to the old master.

B The slave was not promoted correctly with <code>SLAVEOF NO ONE</code>.

C Clients have not updated their configuration to point to the new master.

D The old master is still replicating data to the new master.

💡 Hint

Think about what clients need to do after failover.

Clients must update their connection settings to the new master; otherwise, they keep connecting to the old master.

❓ optimization

expert

Optimizing manual failover to minimize downtime

Which approach best minimizes downtime during a manual failover in Redis Sentinel?

A Restart all Redis instances to refresh connections before failover.

B Disable Sentinel during failover to prevent automatic interference.

C Manually stop the old master, promote the slave, then update clients after failover completes.

D Pre-configure clients with multiple master addresses and use Sentinel notifications to switch automatically.

💡 Hint

Consider how to automate client switching to reduce manual steps.

Pre-configuring clients to listen to Sentinel notifications allows automatic and fast switching to the new master, minimizing downtime.