I am attempting to extend a web application with two zones (default and
internet).

When I extend a web application on a single-server installation, if I
naviage to the extended url, I am redirected to the initial site. For
example, if the URL for the initial site (default zone) is
http://server:9998 and the URL for the extended site (internet zone) is
http://server:9999, I am automatically redirected to http://server:9998
when trying to access http://server:9999. When I perform this activity
on a multiple-server installation, it behaves as expected.

Is this something that behaves differently between a single-server and
multiple-server installation? Could there be something that I botched
during the installation of the single-server installation? Does anyone
have any suggestions for things to try to make both installations
behave the same way?