DNSPerf and ResPerf are free tools developed by Nominum that make it
simple to gather accurate latency and throughput metrics for Domain
Name System (DNS) servers. The latest version of the DNSPerf and
ResPerf can be used with test files that include IPv6 queries.

DNSPerf "self-paces" the DNS query load to simulate network conditions.
New features in DNSPerf improve the precision of latency measurements
and allow for per packet per-query latency reporting is possible.
DNSPerf is now multithreaded, multiple DNSPerf clients can be supported
in multicore systems (each client requires two cores). The output of
DNSPerf has also been improved so it is more concise and useful.
Latency data can be used to make detailed graphs so it is simple for
network operators to take advantage of the data.

ResPerf systematically increases the query rate and monitors the
response rate to simulate caching DNS services.