How can DNS-based traffic management support failover?

How can DNS-based traffic management support failover?

• A. By always routing traffic to the closest endpoint regardless of health.
• B. By directing traffic away from unhealthy endpoints using health checks and DNS responses with failover policies.
• C. By static IP routing without health checks.
• D. By using DNS to automatically scale resources without checks.

Answer: (B)

The main idea is that DNS-based traffic management can direct clients to healthy endpoints by using health checks and policy-driven DNS responses. In practice, a DNS system continuously tests each endpoint’s availability. If the primary endpoint is healthy, DNS returns its IP, so users reach that site. If a health check detects a problem, the DNS response changes to point to a backup, healthy endpoint, following a failover policy (for example, prioritizing a secondary site or distributing load across multiple healthy targets). The speed of this switch depends on DNS TTLs and caching: shorter TTLs allow quicker failover, while longer TTLs reduce churn but slow down recovery. The other options fail because they ignore health status or static configurations. Always routing to the closest endpoint ignores failures. Static IP routing without health checks cannot adapt when an endpoint goes down. Using DNS to scale resources without checks does not address failover or health-based redirection.

The main idea is that DNS-based traffic management can direct clients to healthy endpoints by using health checks and policy-driven DNS responses. In practice, a DNS system continuously tests each endpoint’s availability. If the primary endpoint is healthy, DNS returns its IP, so users reach that site. If a health check detects a problem, the DNS response changes to point to a backup, healthy endpoint, following a failover policy (for example, prioritizing a secondary site or distributing load across multiple healthy targets). The speed of this switch depends on DNS TTLs and caching: shorter TTLs allow quicker failover, while longer TTLs reduce churn but slow down recovery.

The other options fail because they ignore health status or static configurations. Always routing to the closest endpoint ignores failures. Static IP routing without health checks cannot adapt when an endpoint goes down. Using DNS to scale resources without checks does not address failover or health-based redirection.