Hi,
There is an example question posted:
You set up an autoscaling managed instance group to serve web traffic for an upcoming launch. After configuring the instance group as a backend service to an HTTP(S) load balancer, you notice that virtual machine (VM) instances are being terminated and re-launched every minute. The instances do not have a public IP address. You have verified that the appropriate web response is coming from each instance using the curl command. You want to ensure that the backend is configured correctly. What should you do?
A. Ensure that a firewall rule exists to allow source traffic on HTTP/HTTPS to reach the load balancer.
B. Assign a public IP to each instance, and configure a firewall rule to allow the load balancer to reach the instance public IP.
C. Ensure that a firewall rule exists to allow load balancer health checks to reach the instances in the instance group.
D. Create a tag on each instance with the name of the load balancer. Configure a firewall rule with the name of the load balancer as the source and the instance tag as the destination.
I believe the answer is C.
However there's a problem with C. Let me know what you think. So, in GCP a Load Balancer (LB) can conceivably be used without a Managed Instance Group (MIG) and vice versa. They are independent technologies. Both a LB and a MIG have their own health checks. A LB health check adds and removes an instance from the LB. A MIG health check can terminate and replace the instance. In this question, the instances are being terminated. That means, it's a MIG health check, not a LB health check. But answer C says "load balancer health check". It should say "the MIG health check", or else merely "health check", but not "load balancer health check".
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