FAQ

• What is a Traffic Manager “DNS query”?

  Whenever users access your applications, your service name is mapped to the IP address with the DNS query. By providing different responses to different DNS queries, Traffic Manager can make the incoming traffic of your several hosted Azure services achieve load balance, no matter whether these services are operated in the same data center or different data centers in China.

  Traffic Manager provides several load-balance methods, including performance, failover and round robin. Applying these methods can effectively manage traffic, ensure higher performance, availability and recovery capability.

• What is Traffic Manager “Health Check”?

  Applying Traffic Manager, you can utilize Azure service endpoints for monitoring and hosting, and Traffic Manager can also supply automatic failover when a service goes down, so as to improve availability of critical applications.

  Therefore, Traffic Manager will continuously monitor the health of each service endpoint. When these “Health Checks” detect that a service has goes down, Traffic Manager re-routes traffic to the other services.

• Are all pricing of the load-balancing methods the same?

  Yes. No matter which load-balance method is used, pricing for DNS query and health checks are the same.

• How to reduce Traffic Manager bill?

  The PC of the end user will not directly contact the name server of the traffic manager while performing a DNS query. Instead, these queries will be sent by the "recursive" DNS server run by the enterprise and the ISP. These servers cache the DNS responses, so that other users' queries can be processed quickly. Meanwhile, these cached responses will not reach the Traffic Manager name server, thus no cost is incurred.

  The cache duration is determined by the “TTL” parameters in the original DNS response. This parameter is configurable in Traffic Manager with a default value of 300s and minimal value of 30s.

  The larger TTL can be applied to increase the quantity of the completed cache of the recursive DNS server, so as to decrease DNS query fees. However, increasing the cache will also affect the speed for the end user receiving status changes in endpoint (that is, in case of failure of an endpoint, the failover time of your end user will be extended). Thus we do not recommend using extremely large TTL values.

  Likewise, if the TTL is quite small, the failover speed will become faster, while due to the decreased cache, the query times for the name server of the Traffic Manager will increase.

  By configuring the TTL value by yourself, Traffic Manager allows you to set the optimal TTL value based on the business needs of the application.