A Guide to Private Geo-DNS with a Cross-Region Failover Group

By Kenny Lai, Alibaba Cloud Solution Architect

Many MNCs provide geo-optimized resources to serve customers with local resources. To allow a single URL to resolve to a different geo-location server, a geo-aware DNS is required. To solve this issue, Alibaba Cloud offers a geo-DNS.

Customers also want high assurance that the server return from the DNS is always up and running. We need a way to define the health check and allow DNS to return to the backup server in case the primary server fails.

With Alibaba Cloud's GTM, we can serve both requirements with a single product. Let's take a look!

First, we create a new GTM instance in our console.

The most recently purchased instance will appear on the GTM list. Next, click "Configure".

Two options will appear.

Click "Advanced Settings".

The configuration of the GTM will appear. We are going to define two address pools, one for an HK server and one for an SZ server.

Click "Create Address Pool".

In the "Address Pool Name" box, name the pool "hk pool". Then, add the A record you want to resolve from the DNS if it requires the HK server to serve the request.

Click "Confirm." Now, repeat the same process to add the SZ pool.

Next, we need to associate the pool with the access policy.

Click "Add Access Policy" to add a new policy.

Now, we will add an "hk primary policy". This will respond to all DNS requests from outside of Mainland China. The primary group will be an "hk group". If all of the members in the "hk group" fail, it will switch to the "sz group".

Click "Confirm". Then, we will add another group for the SZ policy.

We will add another "sz primary policy" for the DNS request source. Make sure you check all of the boxes under the Mainland China tab.

We will need to tell the GTM how to determine if a server in the group is healthy or not. We can configure the pool to do health checks based on various methods.

First, go to "Address Pool Configurations". Then, click "Add" next to the pool you want to configure for a health check.

There are various ways to do health checks. Based on your requirements, you can select the most suitable way.

Finally, we need to configure the domain name. To define the domain name, click "Edit" on the GTM configuration page.

Give the instance and the Primary Domain the GTM is mapped to a good name. Now, you will notice the CNAME has generated. Next, fill in the "TTL settings", "Load balancing policy", and "Alert Group" in case some servers fail the health checks.

After you have the CNAME, configure your domain entry to return the target domain with the CNAME value shown on your GTM settings screen.

After a few clicks, we defined a geo-DNS with cross-region failover capabilities. This process can be completed in about five minutes.

That's it! Learn more about Alibaba Cloud's Global Traffic Manager at: https://www.alibabacloud.com/products/global-traffic-manager

The views expressed herein are for reference only and don't necessarily represent the official views of Alibaba Cloud.

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A Guide to Private Geo-DNS with a Cross-Region Failover Group

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