Managed instance groups in GCP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Architecture

intermediate

How does a Managed Instance Group handle instance updates?

You have a Managed Instance Group (MIG) with 5 instances running a web application. You want to update the application version on all instances with minimal downtime.

Which behavior best describes how the MIG handles rolling updates?

A It deletes all instances and creates new ones with the updated version at the same time.

B It updates all instances simultaneously, causing downtime during the update.

C It updates instances one at a time, ensuring some instances remain available during the update.

D It requires manual deletion of instances before creating updated ones.

💡 Hint

Think about how to keep the service available during updates.

MIGs perform rolling updates by updating instances one at a time or in small batches. This approach keeps some instances running to serve traffic, minimizing downtime.

❓ service_behavior

intermediate

What happens when an instance in a Managed Instance Group becomes unhealthy?

You have a Managed Instance Group with health checks configured. One instance fails the health check.

What does the Managed Instance Group do automatically?

A It marks the instance as unhealthy and recreates it after a grace period.

B It ignores the unhealthy instance and continues running it.

C It stops the instance but does not replace it automatically.

D It immediately deletes the unhealthy instance and creates a new one.

💡 Hint

Consider how MIGs maintain the desired number of healthy instances.

MIGs mark instances as unhealthy when they fail health checks and recreate them after a grace period to maintain the target size and health.

❓ security

advanced

Which IAM role is required to create and manage Managed Instance Groups securely?

You want to grant a team member permissions to create and manage Managed Instance Groups without giving full project access.

Which IAM role should you assign?

A roles/compute.instanceAdmin.v1

B roles/compute.instanceGroupManager

C roles/compute.networkAdmin

D roles/owner

💡 Hint

Look for the role specific to Managed Instance Groups.

The role roles/compute.instanceGroupManager grants permissions to create and manage Managed Instance Groups without broader project permissions.

❓ Configuration

advanced

What is the effect of setting the 'autohealing' policy in a Managed Instance Group?

You configure an autohealing policy with a health check on a Managed Instance Group.

What happens when an instance fails the health check under this policy?

A The instance is automatically recreated to replace the unhealthy one.

B The instance is stopped but not replaced automatically.

C The instance continues running despite failing the health check.

D The entire Managed Instance Group is deleted and recreated.

💡 Hint

Think about how autohealing maintains instance health.

Autohealing automatically recreates instances that fail health checks to maintain group health and availability.

✅ Best Practice

expert

How should you configure a Managed Instance Group to handle sudden traffic spikes efficiently?

You expect sudden increases in traffic to your application. You want the Managed Instance Group to add instances quickly but avoid excessive costs.

Which configuration best achieves this?

A Set a high fixed number of instances to handle peak traffic at all times.

B Manually add instances when traffic increases and remove them when it decreases.

C Disable autoscaling and rely on load balancer to distribute traffic.

D Use autoscaling based on CPU utilization with a maximum instance limit and cooldown period.

💡 Hint

Consider balancing responsiveness and cost control.

Autoscaling based on CPU utilization with limits and cooldowns allows the group to scale up quickly during spikes and scale down to save costs.