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Difficulty: MediumAmazon Route 53 DNS Configuration and Routing Policies

A company is migrating its primary website at the zone apex (example.com) from an on-premises web server to an Amazon CloudFront distribution. A SysOps Administrator needs to configure Amazon Route 53 to gradually shift 10% of the traffic to the CloudFront distribution, while keeping 90% of the traffic routed to the on-premises web server's public IP address. Which two configurations should the administrator use to achieve this? (Select TWO.)

  1. Create a Weighted A record for the zone apex (example.com) with a weight of 90, targeting the on-premises web server's public IP address.Answer
  2. Create a Weighted Alias A record for the zone apex (example.com) with a weight of 10, targeting the CloudFront distribution domain name.Answer
  3. C
    Create a Weighted CNAME record for the zone apex (example.com) with a weight of 10, targeting the CloudFront distribution domain name.
  4. D
    Create a Weighted CNAME record for the zone apex (example.com) with a weight of 90, targeting the on-premises web server's public IP address.
  5. E
    Create a Failover routing policy for the zone apex (example.com), specifying the on-premises server as the primary target with a failover threshold of 90%.

Answer

To gradually shift traffic at the zone apex, create a Weighted A record targeting the on-premises server's IP address with a weight of 90, and a Weighted Alias A record targeting the CloudFront distribution with a weight of 10.
To route traffic to the zone apex (example.com) while splitting traffic, the administrator must use A records. Since the CloudFront distribution uses a domain name, Route 53 Alias A records must be used for the zone apex because CNAME records are not allowed at the zone apex. The on-premises server uses a static IP address, so a standard A record is appropriate. By setting both as Weighted records with weights of 90 and 10, the traffic is split accordingly.

Step-by-Step Solution

1
Analyze the DNS routing target and limitations of the zone apex.
Identify that the zone apex (example.com) cannot use CNAME records due to DNS protocol specifications, meaning any target using a domain name (like CloudFront) must be routed using an Alias A record.
Ensures the configuration conforms to DNS RFC standards.
2
Determine the appropriate routing policy for percentage-based traffic shifting.
Select Weighted routing rather than Failover routing to achieve the active traffic split (90/10).
Allows gradual migration and testing of the new CloudFront distribution.
3
Configure the two Route 53 resource record sets.
Create one Weighted A record for the on-premises IP address (weight 90) and one Weighted Alias A record for CloudFront (weight 10).
Completes the migration setup while routing traffic correctly across mixed target types.

Key Concept

Using Weighted Routing Policies and Alias Records at the Zone Apex
Estimated Time:1m 30s
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Topics

Amazon Route 53 DNS Configuration and Routing Policies

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