Failover routing for disaster recovery in AWS - Step-by-Step Execution

Process Flow - Failover routing for disaster recovery

User DNS Request

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Check Primary Site Health

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Healthy

User DNS requests are checked against the primary site health. If healthy, traffic routes there; if not, traffic fails over to the secondary site.

Execution Sample

AWS

Route53 failover record setup:
Primary: IP 10.0.0.1, Health check
Secondary: IP 10.0.1.1, no health check
DNS routes based on health

This setup routes user traffic to the primary IP if healthy, else to the secondary IP for disaster recovery.

Process Table

Step	Primary Site Health	DNS Route	User Request Outcome
1	Healthy	Primary IP (10.0.0.1)	Request served by Primary
2	Healthy	Primary IP (10.0.0.1)	Request served by Primary
3	Unhealthy	Secondary IP (10.0.1.1)	Request served by Secondary
4	Unhealthy	Secondary IP (10.0.1.1)	Request served by Secondary
5	Healthy	Primary IP (10.0.0.1)	Request served by Primary

💡 Failover routing switches DNS to secondary IP when primary health check fails, and switches back when primary recovers.

Status Tracker

Variable	Start	After Step 1	After Step 3	After Step 5
Primary Site Health	Healthy	Healthy	Unhealthy	Healthy
DNS Route	Primary IP	Primary IP	Secondary IP	Primary IP
User Request Outcome	N/A	Primary serves	Secondary serves	Primary serves

Key Moments - 2 Insights

Why does DNS route to the secondary IP only when the primary site is unhealthy?

Because Route53 failover routing uses health checks to detect primary site status. When health check fails (see execution_table step 3), DNS switches to secondary IP to maintain service availability.

What happens when the primary site recovers after being unhealthy?

As shown in execution_table step 5, once the primary site health check passes again, DNS routes back to the primary IP automatically to restore normal traffic flow.

Visual Quiz - 3 Questions

Look at the execution_table, what is the DNS route at step 3?

A Primary IP (10.0.0.1)

B Secondary IP (10.0.1.1)

C No route

D Both Primary and Secondary

💡 Hint

Check the 'DNS Route' column at step 3 in the execution_table.

At which step does the user request get served by the secondary site?

A Step 1

B Step 2

C Step 3

D Step 5

💡 Hint

Look at the 'User Request Outcome' column in the execution_table.

If the primary site never recovers, how would the DNS route change after step 3?

A Stay on Secondary IP

B Alternate between Primary and Secondary

C Switch back to Primary IP immediately

D No DNS route

💡 Hint

Refer to the failover logic in concept_flow and execution_table steps 3 and 4.

Concept Snapshot

Failover routing uses DNS health checks to detect if the primary site is down.
If unhealthy, DNS routes traffic to a secondary site.
When primary recovers, DNS switches back automatically.
This ensures continuous service availability during disasters.

Full Transcript

Failover routing for disaster recovery means directing user traffic to a backup site if the main site fails. Route53 uses health checks to monitor the primary site. When healthy, DNS sends users there. If the primary site becomes unhealthy, DNS automatically routes users to the secondary site to keep the service running. When the primary site recovers, traffic switches back. This process helps avoid downtime during failures.