DNS Failover Setup
When your primary region goes down, DNS failover routes traffic to a healthy secondary — automatically, without manual intervention. We configure health-checked DNS routing that detects failures in seconds and fails over cleanly, with proper TTL management and monitoring.
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Health Check Architecture
Health checks probe your application endpoints from multiple locations — not just TCP port checks, but HTTP requests that verify the application actually works (database connected, dependencies healthy). Checks run every 10-30 seconds with configurable failure thresholds (e.g., 3 consecutive failures trigger failover). We use Route 53, Cloudflare, or external monitoring (UptimeRobot, Healthchecks.io) depending on your DNS provider.
Failover Routing Policies
Active-passive: primary region serves all traffic; secondary activates only when primary fails. Active-active: both regions serve traffic with latency-based or weighted routing; unhealthy regions get removed. We configure the routing policy based on your application architecture — active-active requires both regions to handle the full load, active-passive needs faster failover with lower standby cost.
TTL Management
DNS TTLs directly impact failover speed — a 300-second TTL means up to 5 minutes of serving stale records after failover triggers. We set TTLs low enough for acceptable failover time (60 seconds typical) but not so low that DNS query volume becomes a problem. During normal operation, longer TTLs reduce DNS latency. Pre-failover TTL lowering is automated for planned maintenance.
Testing & Validation
We test failover by simulating regional failures — shutting down the primary and verifying traffic routes to the secondary within the expected window. DNS propagation gets verified from multiple global locations. Failback behavior is tested too — ensuring traffic returns to the primary cleanly when it recovers. You get a failover system that's been proven to work, not just configured.
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