This is a piece of software that lets you tunnel IPv4 data through a DNS server. This can be usable in different situations where internet access is firewalled, but DNS queries are allowed.
To use this tunnel, you need control over a real domain (like mytunnel.com), and a server with a static public IP number that does not yet run a DNS server. Then, delegate a subdomain (say, tunnel1.mytunnel.com) to the server.
Now any DNS querys for domains ending with tunnel1.mytunnnel.com will be sent to your server. Start iodined on the server. The first argument is the tunnel IP address (like 192.168.99.1) and the second is the assigned domain (in this case tunnel1.mytunnel.com).