It is a portable app that doesn't require installation. You can download the 32-bit or 64-bit version from its official GitHub repository or SourceForge.
There appears to be no official or widely recognized software tool called "." It is likely a typo for one of several popular networking or development tools.
dnsdist is a highly flexible DNS load balancer and protector.
DNS-SD is a protocol used for discovering services on a local network.
Depending on your original intent, you may be looking for one of the following: 1. dnSpy (Debugger & .NET Assembly Editor)