Abstract DNS64 is an important IPv6 transition technology used in convergence with NAT64 to enable IPv6-only clients to communicate with IPv4-only servers. Several DNS64 implementations have been proposed as a solution. Their performance is an important decision factor for network operators with regard to choosing the most appropriate one among them. To that end, this article proposes a methodology for measuring their performance. The number of resolved queries per second is proposed as performance metric and a step by step procedure is given for its measurement. The design considerations behind the method are also disclosed and the performance requirements for the tester device are specified. The feasibility of our method is proven and its execution is demonstrated in two case studies, which include an empirical analysis of the tester as well as that of three open-source DNS64 implementations. The influence of the rate of existing AAAA records on the performance of the DNS64 server, as well as the influence of the cache hit rate of the DNS64 server on the performance of the DNS64 server are also measured and modeled. Our results and their precision may serve as a reference for further tests.