The software version 17.6.4 is mentioned in the provided document as part of the list of possible answers. Although the document does not explicitly state the software version being used, based on the context and the information given, it appears that 17.6.4 is the version being referred to in the problem details section related to the C9300 product.
The problem details section mentions the C9300 product and the provided list includes 17.6.4 as a possible software version, which could be relevant to the context of the Cisco DNA Center and SDA FE C9300 setup described.