[mod_python] What appears in the browser address window.

I have no idea whether this is a mod_python issue, an Apache issue, an
html issue, or a DNS issue, but here's the problem.  I have a domain,
call it domainx.com, (not real, at least not mine) and the DNS is
evidently set up so that www.domainx.com does map to the static IP of
my office computer.  That is,  when I type www.domainx.com into the
address window of my browser on some other computer, it does fetch the
expected page, but when the browser displays that page, it replaces
the "www.domainx.com" in the address window with the actual IP
address.  I don't like that, and want to know how to make the browser
address window continue to show the URL string that was typed into it.

Thanks,

Ronald