Abstract: Described are computer-based methods and apparatuses, including computer program products, for testing network elements in a communication network. A record file is received, comprising one or more record file elements, each record file element including data indicative of a request received by a network element in a network during normal operation. A virtual client is created for each of one or more identified sources. One or more regenerated requests are generated, each of the one or more regenerated requests being generated based on data in a corresponding record file element from the one or more record file elements. For each of the one or more regenerated requests, the virtual client associated with the regenerated request transmits the regenerated request to a subject network element to test the subject network element, wherein the one or more regenerated requests simulate requests received by the network element during normal operation.