As you may have noticed, SolarWinds has decommissioned the online free tools on DNSstuff. This was a difficult decision because the toolset has been available for over 10 years. I, for one, was a consumer of the toolset long before I started working at SolarWinds.
Unfortunately, the speed at which the DNS-based technologies are moving made it impossible for us to keep up. The amount of upkeep far outweighed the value to our customers. It was decided that rather than omit functionality or have the tools respond with incorrect information that we would sunset the tools. I know that as a longtime user of the tools, I was saddened, but the decision was one that needed to be made.