Recently I had a query from a user on Comcast who is seeing the "It works! This is the default web page for this server." instead of the working site, which I was able to verify by resolving with Verizon or Google DNS servers. My first assumption is that Comcast DNS is the issue, since this is the first complaint after several months of being live, but it makes me second guess my setup - is there something special you need in the records to satisfy Comcast? Is there a good guide on here troubleshooting said issue?
