Assuming you have the libwww-perl (LWP) package installed, you can run the following tests. (Most likely you do have it installed, since you need it to pass mod_perl's make test.)

panic% lwp-request -e -d http://www.example.com

This shows you just the headers; the -d option disables printing the response content. If you just want to see the server version, try:

panic% lwp-request -e -d http://www.example.com | egrep '^Server:'

Of course, you should use http://www.example.com:port_number if your server is listening to a port other than port 80.