An organization is architecting a multi-region disaster recovery strategy for an externally accessible, mission-critical web application on Google Cloud. The architecture must satisfy the following business continuity requirements: The primary deployment runs behind an external Application Load Balancer in the us-east4 region. A standby deployment runs behind a redundant external Application Load Balancer in the us-central1 region. Client traffic must fail over automatically to the secondary region when the primary region experiences an outage and automatically fail back when it recovers. Downtime during a regional outage must be minimized through fast DNS resolution updates. How should you configure Cloud DNS and health checking to achieve automated cross-region failover and failback?

Create a global health check configured with three source regions targeting the primary forwarding rule IP address, configure a Cloud DNS record set with a Failover routing policy referencing the health check, and set the record TTL to 30–60 seconds.: ### What this solution is This solution implements **automated cross-region failover and failback** by pairing **Cloud DNS Failover routing policies** with **Google Cloud distributed health checks** targeting regional external Application Load Balancer forwarding rules. ### How it meets the requirements * **Automated failover and failback**: Cloud DNS monitors the health of the primary regional forwarding rule IP address using distributed probers across three specified source regions. When the primary forwarding rule fails the configured unhealthy threshold, Cloud DNS automatically steers DNS queries to the backup forwarding rule. When the primary region recovers and health check probes succeed, Cloud DNS automatically fails back traffic. * **Minimized RTO and downtime**: Outage duration is governed by the formula `DNS TTL + (Health Check Interval * Unhealthy Threshold)`. Setting the DNS record **TTL to 30–60 seconds** ensures client caches expire rapidly, redirecting user traffic to the healthy secondary region with minimal delay. ### Key advantages * **Resilience to regional failures**: Cloud DNS is a globally distributed, Anycast-routed service capable of serving DNS answers even if an entire cloud region suffers an outage. * **Standardized health probing**: Requiring exactly three source regions prevents false-positive failovers caused by localized network partitions. * **Zero manual intervention**: Traffic redirection on failure and restoration during recovery occur automatically without operator overhead. ### Why this is optimal This approach aligns with Google Cloud architectural best practices for cross-region disaster recovery, balancing swift failure detection against protection against transient flap errors.

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Cloud Dns Health Check Cross Region Failover

Section: Business continuity plan

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An organization is architecting a multi-region disaster recovery strategy for an externally accessible, mission-critical web application on Google Cloud. The architecture must satisfy the following business continuity requirements:

The primary deployment runs behind an external Application Load Balancer in the us-east4 region.
A standby deployment runs behind a redundant external Application Load Balancer in the us-central1 region.
Client traffic must fail over automatically to the secondary region when the primary region experiences an outage and automatically fail back when it recovers.
Downtime during a regional outage must be minimized through fast DNS resolution updates.

How should you configure Cloud DNS and health checking to achieve automated cross-region failover and failback?

Create an external passthrough Network Load Balancer in each region, set the failover ratio to 0.0, and configure Cloud DNS to use weighted round-robin routing.

Deploy a Cloud Service Mesh service load balancing policy with the spray-to-world algorithm, and configure Cloud DNS with a Geo routing policy with a 3600-second TTL.

Configure a single regional health check in us-east4, attach it directly to the Cloud DNS managed zone, and configure an A record with a 300-second TTL pointing to both forwarding rule IP addresses.

Create a global health check configured with three source regions targeting the primary forwarding rule IP address, configure a Cloud DNS record set with a Failover routing policy referencing the health check, and set the record TTL to 30–60 seconds.

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Cloud Dns Health Check Cross Region Failover

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