A client device in a distributed system sends a request to a server via a network and receives a service time duration from the server. The service time duration corresponds to time that the server spent servicing the request. A processor of the client device compares the service time duration with a dynamically generated service time threshold, and automatically issues one or more alert messages to a network operation center (NOC) when the service time duration is greater than the service time threshold. The service time threshold is dynamically calculated according to historic service time durations received from the server for a plurality of previous requests sent by the client device. The service time threshold is dynamically calculated according to historic service time durations of only previous requests of a same type as the request, where the previous requests sent by the client device are of a plurality of types.