AWS - Route 53

Types of routing policies:

1. Simple routing
2. Weighted routing
3. Latency-based routing
4. Failover routing
5. Geolocation routing
6. Multivalue Answer routing

We can not mix routing policies, only one routing policy can be applied at a time.

Simple Routing Policy:

• If you choose Simple Routing Policy you can only have one record with multiple IP addresses. If you specify multiple values in a record, Route53 returns all values to the users in a random order.

Weighted Routing Policy:

• Weighted Routing Policy lets you split your traffic based on different weights assigned. For example you can send 10% of your traffic to US-EAST-1 and 90% to EU-WEST-01.

Latency Based Routing Policy:

• Latency based routing allows you to route your traffic based on lowest network latency for your end user (i.e. which region will give them the fastest response time). To use latency based routing, you create a latency resource record set for the Amazon EC2 (or ELB) resource in each region that hosts your website. When Amazon Route53 receives a query for your website, it selects the latency resource record set for the region that gives the user the lowest latency. Route53 then responds with the value associated with that resource record set.

Failover Routing Policy:

• Failover routing policy is used when you want to create an active-passive setup. For example, you want your primary site to be in EU-WEST-2 and your secondary DR site in AP-SOUTHEAST-2.
• Route53 will monitor the health of your primary site using a health check.
• A health check monitors the health of your endpoints.
• Create health check using ‘Health Check’ option on Route53 console.
• Associate primary DNS entry with Health Check. Secondary can be without health check.

Geolocation Routing Policy:

• Geolocation routing policy allows you to choose where your traffic will be sent based on geolocation of your user (i.e. location from which the DNS queries originate). For example, you might want all your queries originating from Europe to be sent to fleet of EC2 instances specifically configured for European customers. These servers may have the local language and other configuration for European customers.
• You will have to choose location for a record set.

Multi Value Answer Routing Policy

• If you want to route traffic approximately randomly to multiple resources, such as web servers, you can create on multivalue answer record for each resource and, optionally, associate a Route53 health check with each record. For example, suppose, you manage an HTTP web service with a dozen web servers that each have their own IP addresses. No one web server could handle all of the traffic, but if you create a dozen multi value answer records, Route53 responds to DNS queries with upto eight healthy records in response to each DNS query. Route 53 gives different answers to different DNS resolvers. If a web server becomes unavailable after a resolver caches a response, client software can try another IP address in the response.