Our DNS64 benchmarking program, dns64perf++, is the world’s first standard DNS64 benchmarking tool, which complies with the requirements of RFC 8219 (Benchmarking methodology for IPv6 transition technologies) including DNS64. The aim of our current effort is to check and ensure its accuracy. In this paper, we disclose our measurement method and results.We have found inaccuracies at higher rates, which were caused by the self-correcting timing algorithm. We have replaced the timing algorithm by a simpler one, which resulted in accurate results at any tested rates. We have also tested the corrected version during real measurements: we compared the quality of the measurements results produced by the original and thecorrected version.