1. A method comprising: obtaining events from one or more event logs, the events reflecting failures by one or more network devices in one or more data centers; filtering the events using one or more criteria to obtain a sub-set of the events; determining one or more network stamps of an application; characterizing one or more service levels of individual network devices in the one or more network stamps using the sub-set of the events; and characterizing a service level of the application based on the service levels of the individual network devices in the one or more network stamps.