The development of our final DNS Spoofability system required a significant amount of testing, experimentation, and tweaking by GRC and the terrific group of volunteers who inhabit the GRC newsgroups. To facilitate experiments with the many possible variations in the design of the test, this fully parameterized version was made publicly available (though not publicly linked-to until now).

When we discovered that some routers were crashing, this parameterized testing allowed each router's owner to experimentally determine exactly what aspect of the test was upsetting their individual router. All of this was finally reduced to just two basic tests, the “standard test” that works hard not to crash anyone's router, and the “router crash test” that was deliberately designed to quickly crash any router that could be crashed.

We expect that very few, if any, users will have any need or use for this customizable version of our test. So please don't worry if you're wondering whether you're missing something by wondering whether or why you need this. You don't. But since so many of out testers' routers were easily crashed during the development of our standard test, we have probably not seen the last crashable router. And since custom use of our test might be of interest to anyone wishing to perform further research into DNS spoofability, or to more thoroughly understand how this testing system works, we decided to leave the customizable test publicly available.

Finally, for anyone who is curious about how this DNS spoofability testing system operates, the documentation to support this customizable test provides a thorough explanation of the entire DNS testing system.