What are the correct hostnames for the Knowledge Advanced Content and Search APIs?
Knowledge Advanced REST APIs
The Knowledge Advanced APIs are located at yoursite-irs.custhelp.com/km/api/latest/ for the Content REST API and yoursite-qp.custhelp.com/srt/api/latest/ for the Search REST API. Here yoursite is the name of your Oracle B2C Service site; note that these are the same endpoints for all interfaces. To use interface-specific functionality, supply the interfaceId parameter within the kmauthtoken header.
Further details on integrating with these APIs can be found in the documentation available at Technical Documentation and Sample Code or by visiting /km or /srt on either host in a web browser. All of the endpoints listed in the documentation under "Content" use yoursite-irs; all of those under "Search" use yoursite-qp.
For the curious: "IRS" stands for "IM REST Services" and "QP" for "Query Processor"… "IM" being a legacy term for Authoring.