Failover routing for disaster recovery in AWS - Mini Project: Build & Apply

Failover routing for disaster recovery

📖 Scenario: You are managing a website that must stay online even if one server location fails. To do this, you want to set up failover routing using AWS Route 53. This means if the main server is down, traffic automatically goes to a backup server.

🎯 Goal: Build a Route 53 failover routing configuration with a primary and secondary record to ensure disaster recovery.

📋 What You'll Learn

Create a hosted zone for the domain example.com

Create a primary A record pointing to the main server IP

Create a secondary A record pointing to the backup server IP

Configure failover routing so traffic switches to backup if primary is unhealthy

💡 Why This Matters

🌍 Real World

Failover routing is critical for websites and applications that must stay online even if one server or data center fails. It helps maintain availability and user trust.

💼 Career

Cloud engineers and DevOps professionals often configure DNS failover to ensure high availability and disaster recovery for production systems.

1

Create the hosted zone

Create a Route 53 hosted zone named example.com using the AWS CLI command aws route53 create-hosted-zone with the name example.com.

AWS

# Use AWS CLI to create hosted zone for example.com
# Your code here

Hint

Use a unique string for --caller-reference like a timestamp or random value.

2

Create the primary A record

Create a JSON file named primary-record.json that defines a Route 53 record set with name example.com, type A, TTL 60, value 192.0.2.1, and failover set to PRIMARY. Use this file to create the record with aws route53 change-resource-record-sets.

AWS

aws route53 create-hosted-zone --name example.com --caller-reference unique-string-001
# Create primary-record.json with the primary record details
# Your code here

Hint

Remember to add Failover as PRIMARY and a SetIdentifier.

3

Create the secondary A record

Create a JSON file named secondary-record.json that defines a Route 53 record set with name example.com, type A, TTL 60, value 198.51.100.1, and failover set to SECONDARY. Use this file to create the record with aws route53 change-resource-record-sets.

AWS

{
  "Comment": "Primary failover record",
  "Changes": [
    {
      "Action": "CREATE",
      "ResourceRecordSet": {
        "Name": "example.com.",
        "Type": "A",
        "TTL": 60,
        "ResourceRecords": [{"Value": "192.0.2.1"}],
        "Failover": "PRIMARY",
        "SetIdentifier": "PrimaryServer",
        "HealthCheckId": "healthcheck-primary"
      }
    }
  ]
}
# Create secondary-record.json with the secondary record details
# Your code here

Hint

Set Failover to SECONDARY and use a different SetIdentifier.

4

Configure health checks and complete failover setup

Create two health checks named healthcheck-primary and healthcheck-secondary for the IPs 192.0.2.1 and 198.51.100.1 respectively using aws route53 create-health-check. Then update the record sets to reference these health checks to enable failover routing.

AWS

{
  "Comment": "Primary failover record",
  "Changes": [
    {
      "Action": "CREATE",
      "ResourceRecordSet": {
        "Name": "example.com.",
        "Type": "A",
        "TTL": 60,
        "ResourceRecords": [{"Value": "192.0.2.1"}],
        "Failover": "PRIMARY",
        "SetIdentifier": "PrimaryServer",
        "HealthCheckId": "healthcheck-primary"
      }
    }
  ]
}
{
  "Comment": "Secondary failover record",
  "Changes": [
    {
      "Action": "CREATE",
      "ResourceRecordSet": {
        "Name": "example.com.",
        "Type": "A",
        "TTL": 60,
        "ResourceRecords": [{"Value": "198.51.100.1"}],
        "Failover": "SECONDARY",
        "SetIdentifier": "SecondaryServer",
        "HealthCheckId": "healthcheck-secondary"
      }
    }
  ]
}
# Create health checks for primary and secondary IPs
# Your code here

Hint

Use different --caller-reference values for each health check.

Practice

1. What is the main purpose of failover routing in disaster recovery?

easy

A. To block all traffic during maintenance

B. To increase the speed of the primary server

C. To reduce the cost of cloud services

D. To automatically send users to a backup server if the main server fails

Solution

1. Step 1: Understand failover routing purpose

   Failover routing is designed to keep services available by switching traffic to a backup if the main server fails.

2. Step 2: Eliminate unrelated options

   Options about speed, cost, or blocking traffic do not describe failover routing's main goal.

3. Final Answer:

   To automatically send users to a backup server if the main server fails -> Option D

4. Quick Check:

   Failover routing = automatic backup switch [OK]

Hint: Failover means switch to backup when main fails [OK]

Common Mistakes:

• Confusing failover with performance improvement
• Thinking failover blocks traffic
• Assuming failover reduces costs

2. Which AWS Route 53 routing policy is used to implement failover routing?

easy

A. Geolocation routing policy

B. Latency routing policy

C. Failover routing policy

D. Weighted routing policy

Solution

1. Step 1: Identify routing policies in Route 53

   Route 53 offers several routing policies, including latency, geolocation, weighted, and failover.

2. Step 2: Match failover routing policy to disaster recovery

   Failover routing policy is specifically designed to route traffic to a backup when the primary fails.

3. Final Answer:

   Failover routing policy -> Option C

4. Quick Check:

   Failover routing policy = failover setup [OK]

Hint: Failover routing policy is named for failover use [OK]

Common Mistakes:

• Choosing latency or weighted policies for failover
• Confusing geolocation with failover
• Not knowing Route 53 routing policy names

3. Given this Route 53 failover setup: Primary health check fails, what happens to user traffic?
Primary: IP 10.0.0.1 (health check enabled)
Secondary: IP 10.0.0.2 (backup)

medium

A. Traffic switches to secondary IP 10.0.0.2

B. Traffic is split evenly between primary and secondary

C. Traffic is blocked until primary recovers

D. Traffic continues to primary IP 10.0.0.1

Solution

1. Step 1: Understand health check failure effect

   If the primary health check fails, Route 53 detects the primary is unhealthy.

2. Step 2: Apply failover routing behavior

   Failover routing sends traffic to the secondary (backup) IP when primary is unhealthy.

3. Final Answer:

   Traffic switches to secondary IP 10.0.0.2 -> Option A

4. Quick Check:

   Primary down = traffic to backup [OK]

Hint: Failover sends traffic to backup if primary fails health check [OK]

Common Mistakes:

• Assuming traffic stays on primary despite failure
• Thinking traffic is blocked during failover
• Believing traffic splits evenly without weighting

4. You configured failover routing but traffic never switches to the backup server during primary failure. What is the most likely cause?

medium

A. Latency routing policy is used instead of failover

B. Health check is not associated with the primary record

C. Backup server IP address is incorrect

D. TTL value is set to zero

Solution

1. Step 1: Check health check association

   Failover routing requires the primary record to have a health check to detect failure.

2. Step 2: Understand impact of missing health check

   If the health check is missing or not linked, Route 53 never detects primary failure, so no failover occurs.

3. Final Answer:

   Health check is not associated with the primary record -> Option B

4. Quick Check:

   Failover needs health check linked to primary [OK]

Hint: Failover needs health check linked to primary record [OK]

Common Mistakes:

• Ignoring health check association
• Blaming backup IP without checking health check
• Confusing routing policies
• Misunderstanding TTL effects

5. You want to design a disaster recovery setup using Route 53 failover routing with two regions: primary in us-east-1 and backup in us-west-2. Which configuration ensures automatic failover with minimal downtime?

hard

A. Create two records with failover routing; primary record with health check in us-east-1, secondary record without health check in us-west-2

B. Create two records with weighted routing; assign 100% weight to primary and 0% to backup

C. Create two records with geolocation routing; route us-east traffic to primary and us-west traffic to backup

D. Create two records with latency routing; primary in us-east-1 and backup in us-west-2

Solution

1. Step 1: Understand failover routing setup

   Failover routing requires a primary record with a health check and a secondary record without a health check as backup.

2. Step 2: Evaluate options for disaster recovery

   Create two records with failover routing; primary record with health check in us-east-1, secondary record without health check in us-west-2 correctly sets primary with health check and backup without health check, enabling automatic failover.

3. Step 3: Eliminate other options

   Weighted routing does not provide automatic failover; geolocation routes by location, not health; latency routing routes by speed, not failure.

4. Final Answer:

   Create two records with failover routing; primary record with health check in us-east-1, secondary record without health check in us-west-2 -> Option A

5. Quick Check:

   Failover needs primary health check and backup record [OK]

Hint: Primary needs health check; backup record no health check [OK]

Common Mistakes:

• Using weighted routing instead of failover
• Assigning health check to backup record
• Confusing geolocation with failover
• Expecting latency routing to handle failover