Abstract: Described herein are systems and methods for application health based network traffic routing in a geographically distributed cloud service. The domain name system (DNS) resolver can receive, from a service executing on one or more servers hosting a resource, a performance score of the resource. The performance score can be computed from a plurality of metrics determined from a performance monitoring service executing on the one or more servers in communication with the resource. The plurality of metrics can include a first set of performance metrics based on simulated client requests and a second set of performance metrics based on an application's own performance factors. The DNS resolver can receive, from a client, a request to resolve a DNS request. The DNS resolver can transmit, by the DNS resolver, a response to the request identifying the one or more servers selected based on the performance score of the resource.