Weird DNS resolution problems

[Richard Barnes -Listserv]

Here we go....

I work for an ISP.  We have a customer who can ping any IP address in the
world he wants, however when it comes to resolving names, it appears that
the only names he can resolve are:

shop.com -> 207.153.203.136
yahoo.com -> 204.71.200.67

we've tried everything else (including our domain name - blazenet.net) and
nothing.  It just happened to run across the shop.com name, and yahoo.com is
one that I'm sure everyone tries to ping when testing connectivity.  We've
checked for the presence of a hosts file on this machine (Win98SE), and
didn't find one

to further heighten the mystery, this customer can NOT web surf via IP
(www.blazenet.net -> 24.104.2.5).  If he types the blazenet address in his
browser, he gets nothing.

We're sure the system (an IBM Aptiva) is setup correctly because one of our
techs was actually at this guy's house installing the cable modem when we
discovered this problem.  We have no other reports of trouble from anyone in
the same cable modem node.

any suggestions?  the next thing we want to try is to take a laptop out and
see if it experiences the same problems, but it will be a couple of days
before we can get back out there... Even if the laptop functions properly,
I'm still not sure what it means.