Route 53 - Routing Policies Flashcards
What is a Simple Routing Policy in AWS Route 53?
A Simple Routing Policy is the default routing policy where Route 53 responds to DNS queries with one or more IP addresses associated with a domain name.
How does a Simple Routing Policy handle multiple IP addresses?
If multiple IP addresses are specified, Route 53 returns all of them in the response, and the client chooses one randomly for routing.
Can a Simple Routing Policy be associated with health checks?
No, Simple Routing Policies cannot be associated with health checks.
What happens when a Simple Routing Policy includes an Alias Record?
When using an Alias Record with a Simple Routing Policy, only one AWS resource can be specified as the target.
What is an example use case for a Simple Routing Policy?
A Simple Routing Policy is ideal for straightforward DNS configurations where all traffic can be directed to a single or multiple static IP addresses without conditional routing.
What happens when you refresh a website configured with a Simple Routing Policy that has multiple IP addresses?
The client may choose a different IP address randomly from the DNS response, potentially routing to a different backend resource.
What is a Weighted Routing Policy in AWS Route 53?
A Weighted Routing Policy allows you to control the percentage of DNS requests routed to specific resources by assigning weights to each resource.
How is the percentage of traffic determined in a Weighted Routing Policy?
The percentage is calculated as the weight of a record divided by the sum of all weights for records with the same name and type.
Do weights in a Weighted Routing Policy need to sum up to 100?
No, weights are relative and do not need to sum up to 100. They just indicate the proportion of traffic directed to each resource.
What happens if a record’s weight is set to 0 in a Weighted Routing Policy?
A weight of 0 stops traffic from being sent to the associated resource.
Can Weighted Routing Policies be associated with health checks?
Yes, Weighted Routing Policies can be associated with health checks to ensure traffic is only sent to healthy resources.
What is a use case for Weighted Routing Policies?
Common use cases include load balancing across regions, testing new application versions with a small percentage of traffic, and gradually shifting traffic during a migration.
What is required for Weighted Routing Policies to work?
All DNS records must have the same name and type for weights to be applied.
What happens if all records in a Weighted Routing Policy have a weight of 0?
If all records have a weight of 0, Route 53 will distribute traffic equally among the records.
What happens if a resource has the highest weight in a Weighted Routing Policy?
Most DNS responses will direct traffic to that resource, but other resources with non-zero weights will still receive some traffic.
How are records managed in a Weighted Routing Policy in the Route 53 console?
Each record is created separately with the same name and type, but with different weights and optional health checks.
What is the purpose of a Latency-Based Routing Policy in AWS Route 53?
It redirects traffic to the resource with the lowest latency, ensuring users connect to the geographically closest or fastest resource.
How does Route 53 determine the lowest latency for a user?
Route 53 evaluates latency based on how quickly a user can connect to the closest AWS region associated with the resource.
What is a common use case for Latency-Based Routing Policies?
To improve user experience by reducing latency for applications and websites hosted in multiple AWS regions.
Can Latency-Based Routing Policies be combined with health checks?
Yes, they can be combined with health checks to ensure traffic is only routed to healthy resources.
What must you specify when creating a Latency-Based Routing Policy?
You must specify the region of each record, as Route 53 does not automatically determine the region from an IP address.
What happens if latency does not change for a user?
The user will continue to be directed to the same resource with the lowest latency.
What is the purpose of failover routing in Route 53?
To redirect traffic from a primary resource to a secondary (disaster recovery) resource when the primary resource becomes unhealthy.
How does Route 53 determine when to failover to the secondary resource?
By associating a health check with the primary record. If the health check detects that the primary resource is unhealthy, traffic is routed to the secondary resource.
Can failover routing have more than one primary and one secondary resource?
No, failover routing supports only one primary and one secondary resource per failover configuration.
Is a health check mandatory for the primary resource in failover routing?
Yes, a health check must be associated with the primary resource.
Is a health check mandatory for the secondary resource in failover routing?
No, a health check for the secondary resource is optional but recommended.
What happens when the primary resource’s health check becomes healthy again?
Route 53 will automatically fail back to the primary resource.
How does Route 53 handle client DNS requests during failover?
Route 53 responds with the record of the resource (primary or secondary) that is deemed healthy based on the health checks.
What is geolocation routing in Route 53?
It routes traffic based on the geographic location of the user, such as a continent, country, or U.S. state.
What happens if there is no match for a user’s location in geolocation routing?
Traffic is routed to a default record if one is defined.
What are common use cases for geolocation routing?
Website localization
Restricting content distribution
Load balancing based on geographic regions
Can geolocation records be associated with health checks?
Yes, geolocation records can be associated with health checks.
What is required when creating a geolocation record in Route 53?
The routing policy must be set to geolocation.
A specific geographic location must be defined (e.g., continent, country, or U.S. state).
Optionally, a health check can be associated.
What happens if a user is located in a country or region not explicitly defined in geolocation records?
The traffic will be routed to the default record, if it exists.
What is Geoproximity Routing in AWS Route 53?
It routes traffic based on the geographic location of users and resources, allowing adjustments using a “bias” value to shift traffic toward or away from specific resources.
What is a “bias” in Geoproximity Routing?
A bias is a value used to expand or shrink the geographic area that routes traffic to a resource.
What happens when you increase the bias value for a resource?
Increasing the bias expands the geographic area that routes traffic to that resource, directing more traffic to it.
What happens when you decrease the bias value for a resource?
Decreasing the bias shrinks the geographic area that routes traffic to that resource, directing less traffic to it.
Can Geoproximity Routing work with non-AWS resources?
Yes, you can specify the latitude and longitude of non-AWS resources for Geoproximity Routing. (Company’s own data centers)
What tool do you need to use to configure Geoproximity Routing in Route 53?
You must use the advanced Route 53 Traffic Flow feature to configure Geoproximity Routing.
How does Geoproximity Routing handle traffic when bias values are set to zero?
It routes traffic to the closest resource based on the geographic location of the user.
How does Geoproximity Routing differ from Geolocation Routing?
Geolocation Routing: Routes traffic based on the user’s geographic location without adjustment.
Geoproximity Routing: Allows dynamic traffic shifting using bias values to expand or shrink the routing area for resources.
What is IP-Based Routing in AWS Route 53?
It routes traffic based on the client’s IP address by defining CIDR blocks that map to specific endpoints.
What is a CIDR in the context of IP-Based Routing?
CIDR (Classless Inter-Domain Routing) is a range of IP addresses used to group clients for routing purposes.
What is the setup process for IP-Based Routing in Route 53?
Define CIDR blocks for your client IP ranges.
Associate each CIDR block with a specific endpoint (e.g., an EC2 instance).
Route traffic from clients matching a CIDR block to the associated endpoint.
Can IP-Based Routing handle multiple CIDR blocks for a single endpoint?
Yes, multiple CIDR blocks can be associated with the same endpoint.
What is the Multi-Value Routing Policy in AWS Route 53?
It routes traffic to multiple resources and returns multiple values (up to 8) in response to DNS queries.
How does the Multi-Value Routing Policy ensure healthy resources are used?
It integrates with Health Checks, ensuring only healthy resources are returned in the DNS query response.
How is Multi-Value Routing different from Simple Routing?
Multi-Value Routing: Supports Health Checks, ensuring only healthy records are returned.
Simple Routing: Does not support Health Checks, so unhealthy resources may be returned.
What is a key use case for Multi-Value Routing?
It is used for client-side load balancing by returning multiple healthy endpoints for the client to choose from.
Can Multi-Value Routing replace an Elastic Load Balancer (ELB)?
No, it is not a substitute for ELB. It performs client-side load balancing, whereas ELB handles server-side load balancing.
What happens if a resource’s health check fails in Multi-Value Routing?
The unhealthy resource is excluded from the DNS query response.
How can you configure Multi-Value Routing in Route 53?
Create multiple records for the same domain name.
Assign a Multi-Value Routing policy to each record.
Associate each record with a Health Check.
