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Difficulty: MediumAmazon Route 53 DNS Configuration and Routing Policies

A company hosts its main website at the zone apex (example.com). The website is served by regional Application Load Balancers (ALBs) located in the us-east-1 (United States), eu-west-1 (Europe), and ap-southeast-1 (Singapore) regions. The SysOps Administrator has configured Amazon Route 53 Geolocation routing records for the zone apex pointing to each regional ALB. However, users in South America and Africa report that they receive DNS resolution errors when trying to access the website, while users in the United States, Europe, and Singapore can access it successfully. Which configuration change should the SysOps Administrator make to resolve this issue?

  1. A
    Create a CNAME record for example.com with a Geolocation routing policy set to 'Default' pointing to the public DNS name of the ALB in us-east-1.
  2. B
    Change the routing policy for the existing records from Geolocation to Failover, designating us-east-1 as the primary endpoint and eu-west-1 as the secondary endpoint.
  3. Create an Alias A record for example.com with a Geolocation routing policy set to 'Default' pointing to the ALB in us-east-1.Answer
  4. D
    Add a new record for example.com with a Failover routing policy, specifying the ALB in us-east-1 as the primary record without associating a Route 53 health check.

Answer

Create an Alias A record for example.com with a Geolocation routing policy set to 'Default' pointing to the ALB in us-east-1.
The correct answer is to create an Alias A record for the zone apex pointing to the us-east-1 ALB with a Geolocation routing policy set to 'Default'. Geolocation routing requires a default record to handle queries from any location that is not explicitly defined in other records (such as South America and Africa in this scenario). Furthermore, because the target domain is at the zone apex (example.com), standard CNAME records cannot be used. An Alias A record successfully maps the zone apex to the ALB.

Step-by-Step Solution

1
Identify the cause of DNS resolution failure for users in South America and Africa.
Since geolocation routing is used and there are only specific regional records for North America, Europe, and Asia, queries from other locations receive a DNS resolution error because no matching record exists.
Route 53 Geolocation routing requires a default record to handle requests originating from locations that are not explicitly mapped.
2
Select the correct DNS record type for the zone apex (example.com).
An Alias A record must be used because CNAME records are not permitted at the zone apex by standard DNS specifications.
Alias records allow routing traffic for zone apex domains directly to AWS resources like Application Load Balancers.
3
Configure the fallback record.
An Alias A record for example.com is created with the Geolocation routing policy set to 'Default', pointing to the us-east-1 ALB.
This configuration catches all unmapped geolocation queries and routes them to the default regional ALB.

Key Concept

Route 53 Geolocation Routing Default Record and Zone Apex Alias Constraints
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Topics

Amazon Route 53 DNS Configuration and Routing Policies

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