The Microsoft Azure Traffic Manager is a service that forwards requests sent to an Azure Service on the basis of freely definable policies and availabilities to service instances that can be installed worldwide in Azure or in external environments. Three types of forwarding policies can be defined: Performance, Failover, and Round Robin. A policy contains a DNS name. The Traffic Manager replies to requests to this name with the IP address of the next available service instance that fulfills this policy.
The decision of which instance a request is forwarded to is thus based both on the policy and the availability. This makes it possible to distribute the instances of a service worldwide, to normally direct users to the nearest instance, and in case this instance fails, to go to the second-nearest instance, etc. Due to support for including instances operated outside of Azure, failover scenarios can be implemented where access is first made to on-premises instances and, in case of an error, instances in the cloud are accessed.
Azure networking for developers