12. A computer-implemented method comprising: under control of one or more computing devices configured with specific computer-executable instructions, receiving text data representing at least a portion of an utterance; receiving hint data associated with the utterance; determining 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; determining 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; selecting the first NLU component based at least partly on the first ranking data and the second ranking data; and generating a response to the utterance using the first NLU component and the text data.
12. A computer-implemented method comprising: under control of one or more computing devices configured with specific computer-executable instructions, receiving text data representing at least a portion of an utterance; receiving hint data associated with the utterance; determining 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; determining 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; selecting the first NLU component based at least partly on the first ranking data and the second ranking data; and generating a response to the utterance using the first NLU component and the text data. 18. The computer-implemented method of claim 12 , further comprising: receiving audio data representing the utterance; and generating the text data using the audio data and an automatic speech recognition (“ASR”) component.