I recently ran into a problem which looks... a little diffent ;-)
A prospect customer of us bought a domain name. Via their domain
broker company, they mapped the new domain name to our XMPie server's
IP address.
While browsing the domain seemed to properly route to our server,
Helicon-based PURLs failed (error 404).
An investigation showed that our customer configured their domain with
process named "Web Redirection" (which is usually used to map a domain
name to another one, while our customer used it to map the domain name
to our IP address). So, when the HTTP request reached our server, the
domain name was already replaced by our IP address, thus misleading
Helicon (which was expecting the domain name, not an "hardcoded" IP
address).
Creating a "Type A" record in the domain's DNS Zone immediately fixed
the issue.
This to say that when a "company who hosts the domain [says]
everything
is OK at their end", it can be true, but it can be also wrong...