Today, my website, and all of x10hosting, were down, I tried doing a DNS Cachecheck on OpenDNS, to discover the name server wasn't working, this downtime lasted 4 hours... And all x10hosting sites were down.
I use OpenDNS ( http://www.opendns.org/ ) ,but, for other people it was out as well. (Thats how I found out it was broken, I had a PHP program connecting to a server, and people started getting lookup errors, I did a cachecheck on the site, and it changed to "DOES NOT RESOLVE".