12. One or more computer-storage media storing computer-useable instructions that, when executed by a computing device, perform a method for classifying a query, comprising: evaluating a query, by a plurality of domain classifiers, to determine a plurality of domain evaluation results comprising domain evaluation scores, the plurality of domain classifiers corresponding to a plurality of domains; generating category scores for two or more meta-classifier categories based on the plurality of domain evaluation results, a plurality of the generated category scores being greater than a threshold value; selecting one or more meta-classifier categories based on the plurality of generated category scores, the selection being based on a comparison of the plurality of generated category scores, at least one selected meta-classifier category corresponding to two or more domains from the plurality of domains; assigning at least one domain to the query from the two or more domains corresponding to the at least one selected meta-classifier category; and forwarding the assigned at least one domain to a search engine, wherein the category scores for the two or more meta-classifier categories are generated by meta-classifiers based on a non-linear classification model to combine the domain evaluation scores, the meta-classifiers being trained on a first training set of queries that is different from a second training set of queries for the training of at least one domain classifier.
12. One or more computer-storage media storing computer-useable instructions that, when executed by a computing device, perform a method for classifying a query, comprising: evaluating a query, by a plurality of domain classifiers, to determine a plurality of domain evaluation results comprising domain evaluation scores, the plurality of domain classifiers corresponding to a plurality of domains; generating category scores for two or more meta-classifier categories based on the plurality of domain evaluation results, a plurality of the generated category scores being greater than a threshold value; selecting one or more meta-classifier categories based on the plurality of generated category scores, the selection being based on a comparison of the plurality of generated category scores, at least one selected meta-classifier category corresponding to two or more domains from the plurality of domains; assigning at least one domain to the query from the two or more domains corresponding to the at least one selected meta-classifier category; and forwarding the assigned at least one domain to a search engine, wherein the category scores for the two or more meta-classifier categories are generated by meta-classifiers based on a non-linear classification model to combine the domain evaluation scores, the meta-classifiers being trained on a first training set of queries that is different from a second training set of queries for the training of at least one domain classifier. 13. The computer-storage media of claim 12 , wherein the domain evaluation results include domain evaluation scores, and wherein assigning at least one domain to a query further comprises assigning a domain based on a comparison of domain evaluation scores from the two or more domains corresponding to the selected meta-classifier category.