Google Professional Cloud Network Engineer Question 730
Select 2Google Cloud PlatformYour company is running a web application deployed on Google Cloud with an external Application Load Balancer (ALB). You have deployed a new version of the application and plan to gradually redirect traffic from the old backend service to the new one. To ensure a smooth transition, you need to drain the traffic from the old backend while redirecting users to the new backend with minimal disruption. What steps should you take to achieve this?
- A
Set the old backend service's max utilization to 0 and gradually increase the max utilization of the new backend service.
- B
Modify the backend services' weights in the load balancer's URL map to gradually shift traffic from the old backend to the new backend.
- C
Set a draining timeout on the old backend service to allow ongoing connections to complete while directing new connections to the new backend.
- D
Update the load balancer’s frontend IP to point directly to the new backend.
- E
Configure connection draining on the old backend service and set the session affinity to 'Client IP' for both backends.
Show answer and explanation
Correct answers: B, C
Explanation
To gradually redirect traffic from one backend to another using an Application Load Balancer in Google Cloud, you should adjust the backend weights in the load balancer's URL map to control the proportion of traffic sent to each backend. Additionally, configuring a draining timeout on the old backend ensures that ongoing connections are completed without interruption as traffic is shifted. These steps ensure a seamless transition with minimal disruption to the user experience.
- A. Incorrect.
Incorrect: Setting the max utilization to 0 is not a supported method to drain or redirect traffic in an Application Load Balancer. Instead, backend weights and connection draining should be used.
- B. Correct.
Correct: Modifying the backend weights in the load balancer's URL map is the appropriate way to gradually shift traffic between backends in an Application Load Balancer.
- C. Correct.
Correct: Setting a draining timeout on the old backend service ensures that existing connections can finish without disruption while new connections are redirected to the new backend.
- D. Incorrect.
Incorrect: Updating the load balancer’s frontend IP directly to the new backend is not a valid or recommended approach. The load balancer should continue managing traffic routing.
- E. Incorrect.
Incorrect: While connection draining is correct, setting session affinity to 'Client IP' is not specifically required for this scenario and may not align with your traffic management goals.