Okay. Here is an interesting one... please let me put forward three pieces of background info before the question as I think they are necessary to know beforehand...
We (our company) currently has a website... worldhotels.com (www.worldhotels.com
We also currently have an in house PowerDNS controlling the namespace, and doing some rudimentary GEO IP targetting, which points surfers to use one of two different web servers, depending on where they are surfing from.
Right now surfers in our APAC region and US region get pointed to the web server in the US which is at 18.104.22.168
Surfers in EMEA (Europre, Middle East and Africa), get pointed to the server in Germany which is 22.214.171.124
Due to geo-targetting, in order to surf the actual content of the different web server (to see web pages), ... meaning, if you are in America but you would rather surf to and receive web content from the German server,... you must have been directed there either through a resolved DNS request (which is not possible if you are in America, since DNS would have noted your location in the GEO IP database and resolved you to the US mirror) ... or you must have altered your hosts file to point to an alternate server (which will be the case, in tests we have run this is really the only way to do it if you want - say, to look at the German server content while surfing to it from a box in America).
So... GEO IP DNS is working for us. That is not my question, but I wanted to provide some background on my question coming up.
2nd Piece of the Background Puzzle:
Right now, if a user in Germany surfs to worldhotels.com, they receive content from the 126.96.36.199 German server, and if they go to the http://www.worldhotels.com/for-travel-agents.html?L=0
page on the German server, and click the "Login" button at the bottom of the page, the page pops up an iframed js popup. This popup successfully displays its contents, which happens to be a username and password login input boxes.
Clicking on the "Login" does NOT send any kind of HTTP or HTTPS request to the server, it merely uses the code behind the scenes to launch the initial popup which contains an iframe. We have tested this using Fiddler2 and we see repeatedly that no HTTP requests are made while clicking on the button. Just the iframe popup... and...
...the page that is being iframed in the popup is... http://www.worldhotels.com/fileadmin/php_includes/login.php
This surfing behavior, and a successful popup with the correct content appearing in the iframe,... appears/functions normally when a German surfer surfs to the page and clicks the "Login" button. It works. Popup happens. iFrame shows the login box correctly.
It works from a surfer in Germany using IE7 and IE6.
Okay, Last background piece of the puzzle...
When a surfer from the US surfs to the US server (which is what they are routed to via the GEO IP DNS resolution)... the US server residing at 188.8.131.52 ... they can surf to the mirrored http://www.worldhotels.com/for-travel-agents.html?L=0
page on the US server, with exactly the same content on it as the German one.
They can click on the "Login" button at the bottom, and the js / iframed popup appears...
The js / iframed popup ONLY shows the correct content from the iframed http://www.worldhotels.com/fileadmin/php_includes/login.php
...the American surfer is using IE7. IE7 works. It produces the correct results.
However, is the American surfer is using IE6... it does not produce the content inside the js / iframed popup. It is white. It does not say "Page cannot be displayed" (which is what happens if ANY surfer, German or American attempts this popup using IE5.5),... it is just the color white with IE6, from an American user, surfing to the American mirror server.
And just to make it a little weirder... if an American surfer edits their hosts file to FORCE their browser to resolve to the German server at 184.108.40.206, and then surfs to the German server page http://www.worldhotels.com/for-travel-agents.html?L=0
from America, and now tries to use IE6 to surf to it and click the "Login" button at the bottom of the page,...
NOW the js / iframed popup WORKS! and displays the correct iframed content from the German-based http://www.worldhotels.com/fileadmin/php_includes/login.php
on the German server.
So here is my question... DEEP BREATH (thanks to everyone who stayed with me through the whole explanation)....
Why can a US surfer surf to the German site using IE6 and the popup / iframed content functions/displays properly, but as soon as the surfer is being GEO-targetted to the American site using IE6, the popup / iframed content does not display? And conversely, how come the US surfer CAN see the popup iframe content if they are using IE7???
This set of somewhat confusing circumstances has our webmasters and IT departments somewhat befuddled, and we cannot figure out if this is an error at the application layer (meaning there is something about the IE6 browsers used in the US that do NOT take well to this coding), or this is a DNS GEO IP problem (but then WHY does IE7 somehow work? Because a GEO IP problem would be completely inedpendent of ANY browser used, and would produce content or NO content based soley on the DNS resoltuion of a page, which seems highly unlikely since GEO IP DNS works for the ENTIRE site of the mirror and has never malfunctioned before...)