DNS latency based routing. During this lesson, we will configure our environment to take full advantage of the high availability options that are available to us in Route 53, by configuring latency based routing. Before we get started, let us cover our starting scenario which is, we have deployed two web servers in the ap-southeast-1 region, and two web servers in the us-east-1 region. When users go to our website, we want them to go to the region with the lowest latency from their location and then, within that, we want to have the load distributed across the web servers. To do this, we will firstly configure the A resource records for the website and assign them the required values based on the weighting policy that we wish to apply. To create the resource records for our domain name, click create record set. On the right side panel you will see the create record set frame and from here go to the name field and enter www. Ensure that the type is set to A.

Change the TTL seconds to 60. If you leave this as your default, when you go to associate it with a health check, it will recommend you change this value to ensure that the results aren't cached too long in the event of a failure. In the value field enter the IP address of the EC2 instance.

Under routing policy, select weighted from the drop down menu and enter the value of 60--Weight, and in the Set ID, which is a unique descriptive text of up to 128 characters. To differentiate this from other sets we will enter text of weight-1 in Associate with Health Check. Select the radio button, yes and then from the drop down menu, select the corresponding entry and click create to finish.

We will now create the additional resource records for the remaining web servers that we have. Now that we've created our weighted resource records, for the website www.cloudacademylabs1.com we want to create a latency alias resource record for the domain, so that when query's come in, they're handled by the lowest latency resource. Once we've configured the weighted resource records for our website, to configure latency alias resource records for our domain name, click create record set. On the right side panel you will see the create record set frame and from here go to the alias field and select the radio button, yes in the alias target field, and from the drop down menu, select the record set that we just created. In this case, www.cloudacademylabs1.com. Under routing policy, select latency from the drop down menu and select the region. For this we will use us-east-1. Set ID, which is a unique descriptive text of up to 128 characters, to differentiate this from other sets. For this, we will just enter one. In evaluate target health, select the radio button yes and then click create to finish. We will now repeat this to set up our second region. For ap-southeast-1. When we now query DNS we will be directed to the region with the lowest latency and to fulfill our request.