Concepts
The failover routing policy in AWS Route 53 is designed to route traffic to a primary resource when it is healthy and to a secondary (failover) resource when the primary is unhealthy. This policy is essential for creating active-passive failover configurations where a standby resource takes over in the event of a failure.
Example Scenario:
You have two versions of your website hosted in different regions. You want to serve traffic from the primary site, but in case the primary site fails, you want to seamlessly direct traffic to the secondary site.
- For primary resource record set:
- Name:
example.com - Type:
A - Set ID:
Primary - Health Check: Attached to the endpoint for health checking
- Failover:
PRIMARY
- Name:
- For secondary (failover) resource record set:
- Name:
example.com - Type:
A - Set ID:
Secondary - Health Check: Attached to the endpoint for health checking
- Failover:
SECONDARY
- Name:
When the health check associated with the primary site detects an outage, Route 53 will automatically route traffic to the secondary site.
Weighted Routing Policy
Weighted routing allows you to assign weights to your resource record sets which determine the proportion of DNS queries that go to each resource. This policy is suitable for load distribution and traffic splitting for A/B testing.
Example Scenario:
You want to split traffic between two servers where one server gets 70% of the traffic, and another gets 30%.
- For server 1 resource record set:
- Name:
example.com - Type:
A - Set ID:
Server1 - Weight:
70 - Health Check: (Optional) If required
- Name:
- For server 2 resource record set:
- Name:
example.com - Type:
A - Set ID:
Server2 - Weight:
30 - Health Check: (Optional) If required
- Name:
By adjusting the weights, Route 53 distributes traffic across both servers based on the specified percentages.
Latency-Based Routing Policy
Latency-based routing is used to direct traffic to the resource that will give users the lowest possible latency by considering the user’s location and the latency experienced when reaching each AWS region.
Example Scenario:
You host your application in both the US West (Oregon) and the US East (N. Virginia) regions. You want to route users to the region that will provide them with the quickest response time.
- For the US West resource record set:
- Name:
example.com - Type:
A - Set ID:
US-West - Latency Region:
us-west-2 - Health Check: (Optional) If required
- Name:
- For the US East resource record set:
- Name:
example.com - Type:
A - Set ID:
US-East - Latency Region:
us-east-1 - Health Check: (Optional) If required
- Name:
Route 53 measures the latency from the user to each region, directing the user to the region that results in the fastest experience.
Comparison of Routing Policies
| Routing Policy | Use Case | Considerations |
|---|---|---|
| Failover | Active-passive failover setups | Requires health checks. Secondary only serves if primary fails. |
| Weighted | Load distribution and traffic splitting | Good for A/B testing. Weights must be assigned to each record. |
| Latency | Route to the lowest latency endpoint | Users are routed based on geographic location and latency metrics. |
In conclusion, AWS Route 53 routing policies are essential tools for high availability, load balancing, and low-latency configurations. Correctly implementing failover, weighted, and latency-based routing policies not only helps in optimizing user experience but also plays a critical role in maintaining operational resilience. For the AWS Certified SysOps Administrator – Associate (SOA-C02) exam, understanding these routing policies’ use cases, setup, and the ability to decide when to use which policy is crucial.
Answer the Questions in Comment Section
True/False: AWS Route 53 can be used to route users to a healthy region in case one region fails.
- True
- False
Answer: True
Explanation: AWS Route 53 Failover routing policy is designed to route traffic to a backup location if the primary site fails, thereby ensuring high availability.
Which Route 53 routing policy allows you to split traffic between two or more resources based on specified weights?
- Failover
- Geolocation
- Weighted
- Latency
Answer: Weighted
Explanation: The Weighted routing policy in AWS Route 53 allows you to assign weights to resource records, which dictate what portion of traffic goes to each resource.
True/False: Latency-based routing in AWS Route 53 always routes a request to the resource with the absolute lowest latency.
- True
- False
Answer: False
Explanation: Latency-based routing in AWS Route 53 routes traffic to the resource that provides the lowest possible latency based on historical data and not necessarily the one with the absolute lowest latency at the moment of the request.
Which AWS Route 53 routing policy is most suitable for directing traffic to the endpoint with the best performance for the user?
- Weighted
- Failover
- Multivalue answer
- Latency
Answer: Latency
Explanation: The Latency routing policy enables AWS Route 53 to route traffic to the region that provides the best latency performance for the end user.
True/False: Route 53’s Geoproximity routing policy lets you control how traffic is distributed according to the geographic location of your users and your resources.
- True
- False
Answer: True
Explanation: Geoproximity routing policy in AWS Route 53 helps route traffic based on the geographic location of your users and your resources, optionally using ‘bias’ to fine-tune the size of the geographic region.
True/False: All Route 53 routing policies support health checks.
- True
- False
Answer: True
Explanation: AWS Route 53 supports health checks for all routing policies, allowing you to route traffic only to healthy endpoints.
Which Route 53 routing policy utilizes DNS records to direct traffic to multiple backend resources based on predefined ratios?
- Simple
- Failover
- Weighted
- Geolocation
Answer: Weighted
Explanation: The Weighted routing policy uses weights set on DNS records to distribute traffic among multiple resources.
True/False: Route 53’s Multivalue Answer routing policy provides the same functionality as a load balancer.
- True
- False
Answer: False
Explanation: Multivalue Answer routing policy allows you to configure Route 53 to return multiple values, such as IP addresses for your web servers, in response to DNS queries. However, it does not offer the full functionality of a load balancer, such as session persistence or detailed health checks.
When using the Failover routing policy in Route 53, which record serves as the backup in the event the primary resource is unhealthy?
- Secondary record
- Tertiary record
- Failover record
- None of the above
Answer: Secondary record
Explanation: In a Failover routing policy, there is a primary record that serves traffic during normal operation, and a secondary record that takes over when the primary is deemed unhealthy.
True/False: Weighted Routing Policy supports only integer values for assigning weights to resources.
- True
- False
Answer: True
Explanation: In AWS Route 53, the Weighted routing policy requires integer values to be assigned as weights for corresponding resources.
In a Latency-based routing policy, Route 53 will prioritize routing to resources in which of the following ways?
- Based on user proximity to the resource
- Based on the highest available bandwidth
- Based on the lowest historical latency
- None of the above
Answer: Based on the lowest historical latency
Explanation: Latency-based routing priorities are based on the lowest historical latency to route traffic to the most efficient region available for the user.
True/False: You can use Route 53 Traffic Flow to visually manage how your users are routed to application endpoints.
- True
- False
Answer: True
Explanation: AWS Route 53 Traffic Flow is a visual editor that simplifies the process of managing how users are routed to application endpoints.
This blog post on Route 53 routing policies was really helpful! Thanks!
Can someone explain how latency-based routing works in more detail?
Great post! I’m preparing for the SOA-C02 exam, and this is very timely.
How does the failover routing policy ensure high availability?
The weighted routing policy is a bit confusing. Can someone clarify how it’s useful?
This blog clarified a lot of my doubts. Thanks!
Weighted routing seems cool, but won’t it add complexity to my DNS management?
This guide on Route 53 routing policies was exactly what I needed. Appreciate it!