DNS Geo Lookups

Question

I have been looking at setting up Geo DNS routing using Azure Traffic Manager (Performance mode). Basically I have an application (Web App and Azure SQL Database) set-up in East US, North Europe and Australia East. For compliance reasons data cannot be shared between data centres, and I do not want the user to have to make a choice regarding which data centre the use:

• us.app.com
• eu.app.com
• au.app.com

I want to be able to use app.com and then have that routed based on the user location. All of which Traffic Manager does - however it will also fail over to other data centres if the closest data centre is unavailable. I don't want the fail-over behaviour - if for some reason the Web App is down in the closest region, I want the user to receive an error.

Has anyone experience of any other providers that offer such a facility? Can the fail-over behaviour be turned off on Traffic Manager.

Answer 1

Interesting question!

Firstly, please note that the 'Performance' mode routing in Traffic Manager is not guaranteed to route a given user to the same data center if that use travels...for example, if an EU user accesses the service whilst visiting the US, they will be routed to the US endpoint. For this reason, where there is a strong constraint to link a user with a particular region, an application-level re-direct may be required.

To address the question you actually asked...there's no built-in ability to disable endpoint monitoring / failover in Traffic Manager today. As a workaround, I suggest making a placeholder site that hosts an error page using Azure Web Apps, then using nested Traffic Manager profiles as follows

• 3 child profiles, each with 2 endpoints - one of your service endpoints plus the error page web app. These will use the 'Priority' traffic-routing method (aka 'failover' if you're using the old ASM APIs)

• 1 parent profile, with 3 endpoints, namely the 3 child profiles above. This should use the 'Performance' traffic-routing method. You'll have to specify the location of each endpoint, which should be the same as the app that it contains.

In this way, if one of your apps fails, traffic will be directed to the error page site instead of to the other apps.

Configuring nested Traffic Manager profiles isn't supported in the Azure Portal today. You will need to use Azure PowerShell or Azure CLI (which supports Windows, Linux and Mac OS)

Regards,

Jonathan Tuliani Program Manager Azure Networking - DNS and Traffic Manager