1. A method, in a data processing system comprising a processor and a memory, for answering an input question, the method comprising: receiving, in the data processing system, an input question to be answered from a source; processing, by the data processing system, the input question to extract one or more features of the input question; comparing, by the data processing system, the extracted one or more features to cached features stored in one or more entries of a question and answer (QA) cache of the data processing system; determining, by the data processing system, whether there is a matching entry in the one or more entries of the QA cache based on results of the comparing, wherein determining whether there is a matching entry in the one or more entries of the QA cache comprises: generating, for each entry in the QA cache, a match value indicative of a degree of matching between the one or more extracted features of the input question to cached features of the entry in the QA cache; and comparing the match value to one or more threshold values indicating one or more requisite degrees of similarity between the input question and an entry in the QA cache, wherein: in response to the match value equaling or exceeding a first threshold value, a corresponding entry is determined to match the input question, and in response to the match value being less than the first threshold value but the match value being equal to or greater than a second threshold value, determining that the corresponding entry is sufficiently similar for updating the corresponding entry with the one or more extracted features of the input question; retrieving, by the data processing system, in response to a matching entry being present in the one or more entries of the QA cache, candidate answer information from the matching entry; and returning, by the data processing system, the retrieved candidate answer information to the source of the input question as candidate answer information for answering the input question.