Weighted Routing in Route 53: How It Works and When to Use

Weighted routing in AWS Route 53 lets you split internet traffic across multiple resources by assigning weights to each. This means you can control how much traffic goes to each server or endpoint based on the weights you set.

How It Works

Imagine you have two lemonade stands and want to send more customers to one than the other. Weighted routing in Route 53 works like assigning a popularity score to each stand. If one stand has a weight of 70 and the other 30, about 70% of customers will be directed to the first stand and 30% to the second.

In technical terms, Route 53 uses the weights you assign to DNS records to decide how to distribute traffic. When someone looks up your domain, Route 53 chooses which IP address to return based on these weights. This helps balance load or test new versions of your app by sending a small portion of traffic to a new server.

Example

This example shows how to create two weighted records in Route 53, sending 80% of traffic to one server and 20% to another.

json

{
  "Comment": "Create weighted routing records",
  "Changes": [
    {
      "Action": "CREATE",
      "ResourceRecordSet": {
        "Name": "example.com.",
        "Type": "A",
        "SetIdentifier": "PrimaryServer",
        "Weight": 80,
        "TTL": 60,
        "ResourceRecords": [
          {"Value": "192.0.2.1"}
        ]
      }
    },
    {
      "Action": "CREATE",
      "ResourceRecordSet": {
        "Name": "example.com.",
        "Type": "A",
        "SetIdentifier": "BackupServer",
        "Weight": 20,
        "TTL": 60,
        "ResourceRecords": [
          {"Value": "192.0.2.2"}
        ]
      }
    }
  ]
}

Output

Two DNS A records created for example.com with weights 80 and 20 directing traffic accordingly.

When to Use

Weighted routing is useful when you want to control traffic flow between multiple servers or endpoints. For example:

• Testing a new version of your website by sending a small percentage of users to it.
• Gradually shifting traffic from an old server to a new one without downtime.
• Distributing load unevenly based on server capacity.

This method helps you manage risk and optimize performance by controlling how users reach your resources.

Key Points

• Weighted routing splits traffic based on assigned weights.
• Weights are relative; higher weight means more traffic.
• Useful for gradual deployments and load balancing.
• Works at the DNS level by returning different IPs.

Key Takeaways

Weighted routing in Route 53 controls traffic distribution by assigning weights to DNS records.

It helps balance load or test new resources by sending a percentage of users to each endpoint.

Weights are relative and determine the proportion of traffic each resource receives.

Use weighted routing for gradual rollouts, load management, and risk reduction.