1. A computer program product comprising a computer readable storage medium having a computer readable program stored therein, wherein the computer readable program, when executed on a computing device, causes the computing device to: receive an input question to be answered from a source; process the input question to extract one or more features of the input question; compare 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; determine whether there is a matching entry in the one or more entries of the QA cache, wherein the computer readable program to determine whether there is a matching entry in the one or more entries of the QA cache further causes the computing device to: generate, 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 compare 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 the computer readable program further causes the computing device to determine a corresponding entry 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, the computer readable program further causes the computing device to determine that the corresponding entry is sufficiently similar for updating the corresponding entry with the one or more extracted features of the input question; retrieve, 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 return the retrieved candidate answer information to the source of the input question as candidate answer information for answering the input question.