This counter tracks how many prefix consistency queries this checker successfully processed to completion. This is the useful-work-done counter for the checker, and an admin sanity-checks system health by confirming this number rises roughly in line with cefCCQueriesSent, since a large gap between sent and checked would indicate queries are being lost somewhere in the pipeline. Over a scan cycle covering the full FIB, an admin might expect this counter to eventually match the total prefix count reported for that checker type, confirming full coverage.