1. A system comprising: computer-readable memory storing executable instructions; and one or more processors in communication with the computer-readable memory, wherein the one or more processors are programmed by the executable instructions to: receive text data representing at least a portion of an utterance; receive hint data associated with the utterance; determine first ranking data using the text data and the hint data, wherein the first ranking data represents a relative rank of a first natural language understanding (“NLU”) component of a plurality of NLU components, wherein the first NLU component is associated with a first domain; determine second ranking data using the text data and the hint data, wherein the second ranking data represents a relative rank of a second NLU component of the plurality of NLU components, wherein the second NLU component is associated with a second domain; select the first NLU component based at least partly on the first ranking data and the second ranking data; and generate a response to the utterance using the first NLU component and the text data.