Explanation

Correct Answer: A) Rolling update

Why Rolling Update is the correct choice:

1. Maintains capacity: Rolling updates deploy new versions to a Managed Instance Group (MIG) by gradually replacing instances while maintaining the desired capacity throughout the process.

2. Zero-downtime deployment: Rolling updates work by:

   • Creating new instances with the updated template
   • Adding them to the MIG
   • Removing old instances
   • This happens in batches to ensure the MIG always has the required number of healthy instances

3. Controlled deployment: You can configure parameters like:

   • Maximum number of instances being updated at once
   • Minimum number of healthy instances during the update
   • Instance replacement method (proactive or opportunistic)

Why other options are incorrect:

• B) Recreate instances: This would terminate all instances at once and create new ones, causing downtime and reducing capacity during the transition.

• C) Manual replacement: This is inefficient and error-prone, requiring manual intervention for each instance replacement.

• D) Stop autoscaling: This doesn't help with version deployment; it only stops the autoscaling feature but doesn't provide a mechanism for updating instances to a new version.

Key takeaway: When deploying new versions to a Managed Instance Group while maintaining capacity and minimizing downtime, rolling updates are the recommended Google Cloud approach.