Which deployment strategy uses two production-like environments and allows switching traffic between them to achieve zero-downtime updates and easy rollback?

Which deployment strategy uses two production-like environments and allows switching traffic between them to achieve zero-downtime updates and easy rollback?

• A. Rolling deployment
• B. Canary deployment
• C. Blue-green deployment
• D. A/B testing

Answer: (C)

Blue-green deployment keeps two production-like environments: one serving live traffic and a second identical one that is idle. You deploy the new version to the idle environment, validate it, and then switch all user traffic from the current live environment to the new one using the load balancer or DNS. Because the old version remains running and ready, you can switch back instantly if anything goes wrong, achieving zero downtime and easy rollback. This approach contrasts with rolling deployments, which update instances in place and can risk transient downtime, and with canary or A/B testing, which expose only a subset of users to new versions rather than providing an immediate full switch.

Blue-green deployment keeps two production-like environments: one serving live traffic and a second identical one that is idle. You deploy the new version to the idle environment, validate it, and then switch all user traffic from the current live environment to the new one using the load balancer or DNS. Because the old version remains running and ready, you can switch back instantly if anything goes wrong, achieving zero downtime and easy rollback. This approach contrasts with rolling deployments, which update instances in place and can risk transient downtime, and with canary or A/B testing, which expose only a subset of users to new versions rather than providing an immediate full switch.