Which practice helps minimize downtime during upgrades and supports quick rollback?

Which practice helps minimize downtime during upgrades and supports quick rollback?

• A. Upgrading all instances simultaneously without tests.
• B. Taking the system offline for hours during upgrades.
• C. Rolling updates with load balancing to shift traffic away from instances being upgraded.
• D. Making upgrades only in development.

Answer: (C)

The idea is to upgrade without taking the whole system offline by updating instances in a sequence while a load balancer keeps handling requests. As each instance finishes its upgrade, it becomes healthy and starts receiving traffic again, but you shift traffic away from the instance currently being updated so users aren’t affected. This approach gives you paging visibility—health checks confirm an instance is ready before it takes on more load—and it makes rollback quick because the traffic can be redirected back to the previously stable version or to any still-unupgraded instances if something goes wrong. In contrast, upgrading all at once risks a service outage, taking the system offline for hours guarantees downtime, and making upgrades only in development doesn’t address the production environment at all.

The idea is to upgrade without taking the whole system offline by updating instances in a sequence while a load balancer keeps handling requests. As each instance finishes its upgrade, it becomes healthy and starts receiving traffic again, but you shift traffic away from the instance currently being updated so users aren’t affected. This approach gives you paging visibility—health checks confirm an instance is ready before it takes on more load—and it makes rollback quick because the traffic can be redirected back to the previously stable version or to any still-unupgraded instances if something goes wrong. In contrast, upgrading all at once risks a service outage, taking the system offline for hours guarantees downtime, and making upgrades only in development doesn’t address the production environment at all.