TXT Record XSS
I am half serious, but how about making HTML served in TXT records a standard trick for serving small web pages very quickly? There are way fewer network round trips:<p><pre><code>  1. DNS query for TXT record for example.com
  2. DNS reply with HTML content
</code></pre>
Compared with the traditional 7 steps:<p><pre><code>  1. DNS query for A record for example.com
  2. DNS reply with x.x.x.x
  3. TCP SYN to port 80
  4. TCP SYN/ACK
  5. TCP ACK
  6. HTTP GET
  7. HTTP reply with HTML content
</code></pre>
It would also make the content super-distributed, super-reliable, as DNS servers cache it worldwide (and for free so it would reduce hosting costs :D). Also TXT records can contain more than 255 bytes as long as they are split on multiple strings of 255 bytes in a DNS reply.<p>Again, I am only half serious, but this is an interesting thought experiment...<p>Edit: oddtarball: DNSSEC would solve spoofing. And updates should take no longer than the DNS TTL to propagate: the TTL is under your control; you could set it to 60 seconds if you wanted. It is a common, false misconception that <i>many</i> DNS resolvers ignore the TTL. Some large web provider (was it Amazon? I forget) ran an experiment and demonstrated that across tens or hundreds of thousands of clients wordlwide, 99% of them saw DNS updates propagated within X seconds if the TTL was set to X seconds. Only <1% of DNS resolvers were ignoring it.