DNS problems?

Hi networking gurus. I have a problem. I have a website, www.demo.hoacenter.com. I have an ISP, cox communications. I have a virtual web hosting service, digitalomaha.net. I have a domain name registrar, godaddy.com. Sometimes, I cannot navigate to my website, but I can navigate to other, more famous sites, like Google and Excite and Yahoo. However, by using other ISP's, I can get to the site simultaneously. I have complained to cox communications, and they tell me that I am assigned to three name servers. I have gone to [login to view URL], and performed an advanced NsLookup on my domain, using the cox nameservers. I sometimes get a report that: "[[login to view URL]] returned a non-authoritative response in 47 ms: Name Server Failed" The advanced response tells me that the rcode returns "Name Server Failed". But the report doesn't tell me WHICH ONE! Interestingly, I also have another website, hosted on the same server, using same DNS servers, same IP address, that I can get to when [login to view URL] fails. It seems to be tied to [login to view URL] somehow, someway. However, using [login to view URL], I've learned that my entries are OK.... What I need to do is isolate the problem specifically to identify the weak link. I have neither the tools nor the knowledge, beyond what I've described here. In order to point the finger at someone, I need to be able to beat them at the "it's not our fault" game. How can you help? Please do not send me your "stock resume", instead could you give me a two-minute discussion of the usual suspects? Tx, George ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Installation package that will install the software (in ready-to-run condition) on the platform(s) specified in this bid request. 3) Complete ownership and distribution copyrights to all work purchased. ## Platform I'm a windows user. I need something better.