Disclosed are techniques for classifying inquiries in real-time or nearly real-time. These techniques identify or generate a data model that receives and determine one or more classes for the inquiry in real-time or nearly real-time at least by applying a hierarchical set of rules in the data model to the inquiry. A hierarchical class data structure at least by storing and indexing the one or more classes based in part or in whole upon a hierarchical structure of the one or more classes in a non-transitory computer memory.