Just this past week I've had the same problem with the http://www.tzonedigital.com/ domain, which remained unaccesible if you use our ISP's (Telefonica) DNS servers (80.58.61.250 and 80.58.61.254). But using google's DNS (8.8.8.8) servers it is accesible, tested with some others with random results.

Telefonica DNS administrators told me tzonedigital.com's DNS zone is misconfigured and directed me to http://www.intodns.com/tzonedi... and the problems it reports. From the misconfiguration and the fact that DNS servers are queried in a random order, you get non-deterministic errors.

Looks like http://www.intodns.com/021yy.o... is misconfigured too, so it well may be that the problem lies not with Comcast but with 021yy.org.

Just my 2c.

As for getting things fixed via bugzilla reports, I only can say they fixed all the bugs I submitted quite promptly, and they were unrelated things, like Https.WebRequest not working with https uris (fixed) or gtk# glitches (fixing)