Google Professional Cloud Network Engineer Question 405
Single answerGoogle Cloud PlatformYou are designing a Google Cloud Load Balancer for a web application that requires users to maintain their session across multiple requests. The application is hosted on a backend instance group with autoscaling enabled, and you want to ensure that traffic is evenly distributed while keeping users' sessions consistent. Which configuration should you use to achieve this?
- A
Set the load balancer's session affinity to NONE and rely on autoscaling to handle traffic spikes.
- B
Configure the load balancer with session affinity set to CLIENT_IP to ensure requests from the same client are sent to the same backend instance.
- C
Enable session affinity based on GENERATED_COOKIE to ensure session consistency regardless of client IP changes.
- D
Set the serving capacity for the backend instance group to a fixed number of instances to avoid overloading individual backends.
Show answer and explanation
Correct answer: C
Explanation
To maintain session consistency across multiple requests, session affinity is required. Using GENERATED_COOKIE ensures that the load balancer can route requests from the same session to the same backend instance, even when client IPs change. This approach works well with autoscaling, as the load balancer dynamically adjusts backend assignments based on the cookie.
- A. Incorrect.
This option disables session affinity, which would prevent users from maintaining session consistency across requests. While autoscaling handles traffic spikes, it does not address session persistence.
- B. Incorrect.
Using CLIENT_IP for session affinity may not work in scenarios where client IPs change frequently (e.g., mobile networks or proxies), potentially breaking session consistency.
- C. Correct.
GENERATED_COOKIE-based session affinity is ideal for ensuring session consistency regardless of client IP changes. The load balancer generates a cookie that is used to route requests to the same backend instance, maintaining user sessions effectively.
- D. Incorrect.
Fixing the serving capacity to a specific number of instances would limit the flexibility of autoscaling and could lead to performance issues during traffic spikes. This does not address session consistency.