Traffic Manager profile with multiple domains via DNS

Question

Hi!

(Note: this question is mainly regarding configuring the DNS for traffic manager and whether the below settings can work).

We have a website with multiple subdomains, all of which are served by the same app services (there are multiple copies of this app service, all of which have custom domains for the various subdomains set up).

At the moment only the www site has DNS pointed at our traffic manager; we use geographic routing to send any requests for the www site from a certain location to an instance of the web app in East Asia.

The other endpoint in the Traffic Manager Profile is an Application Gateway endpoint, which we use for load balancing. All traffic for the www site is sent to this endpoint.

Other subdomains have DNS that points directly at a single app service; we would like to amend this so that they benefit from the load balancing and failover configuration in Application Gateway.

So, the question: given domains like

www.contoso.com
subdomain1.contoso.com
subdomain2.contoso.com

If we updated the DNS for subdomain1.contoso.com and subdomain2.contoso.com to point at the Traffic Manager address (call it contoso.trafficmanager.net), would Traffic Manager be able to correctly identify that it should send this traffic to the application gateway? (AG is already configured to receive traffic for these domains and distribute them between app services).

Thanks in advance!

Chris.

Answer 1

Hello @Chris Norwood ,

Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.

I understand that you are using Azure Traffic manager with geographic routing with 2 endpoints - one app service for East Asia region and one Application gateway for all other regions and routing the www domain traffic to them but you would like to change the domain mapping of your Traffic manager from root to subdomain and would like to know if the Traffic Manager can correctly identify that it should send this traffic to the Application gateway, provided the Application gateway is already configured to receive traffic for these domains.

As explained in How Traffic Manager Works, Traffic Manager works at the DNS level. It uses DNS responses to direct clients to the appropriate service endpoint. Clients then connect to the service endpoint directly, not through Traffic Manager. Traffic Manager is not a proxy or a gateway. Traffic Manager doesn’t see HTTP traffic between client and server. When using a vanity domain with Azure Traffic Manager, you must use a CNAME to point your vanity domain name to your Traffic Manager domain name.

As long as your application is configured to accept the correct host header for the domain name you’re using, the Traffic manager will route the traffic correctly.

If you map your DNS for the subdomains to point at the Traffic Manager address and the Application gateway along with it's backend pool are configured to accept the the correct host header for those subdomains, the Traffic manager will be able to route the traffic to the Application gateway without any issues.

Kindly let us know if the above helps or you need further assistance on this issue.

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