In Brief:
My company is currently working on a small asp.net website to be used by a set of our customers. The site fails to load in only IE8 in our production environment, instead displaying a general page-not-found error (not a 404 from our server).
Details:
The website is deployed on two servers, QA and Prod. Both servers were cloned from the same image and should have identical settings. They have identical hardware and software. Both servers are outside of our company firewalls, accessible from the internet, as well as our company intranet. The website itself was deployed on both servers from the same build; the only difference is a single line in each site's web.config file pointing the site on Prod to the production database and the site on QA to a test database (whose data is cloned from Prod on a regular basis). I'll refer to our site on the QA server as site.qa.com and our site on the Prod server as site.prod.com.
When site.prod.com is accessed from the company intranet in any browser the site loads and behaves correctly (this includes accessing it in IE8). When site.prod.com is accessed from the internet (as our end users will be accessing it), site.prod.com loads and behaves correctly in Chrome, Firefox, Safari, and IE9. When we attempt to access it in IE8, IE8 returns a page-not-found error, as if the computer accessing site.prod.com is disconnected from the internet.
site.qa.com is accessible on both our intranet and the internet in every browser (including IE8).
I should also note that accessing site.prod.com from both the internet and our intranet uses the same URL and should pass through the same security checks; there's not a special intranet-only way of accessing either site.prod.com or site.qa.com.
More about the servers:
Both QA and Prod are running Windows Server 2008 R2 Standard, Service Pack 1. We are running the website through IIS 7.5, and IIS settings are identical between the two servers (exporting their config files and comparing shows them matching down to the line).
Closing:
At this point we are stumped about why our website fails to load in IE8. It's not an option for us to drop support for IE8, and cloning QA and using that clone as Prod is a temporary solution we're considering, but won't answer our core question, which is: why will IE8 completely fail to load the production site, and only the production site, only when accessed from the internet?
EDIT: The website magically started working (it looks to be one of those errors). I'll post here anything we're able to uncover about this behavior and how it was fixed, in case others are experiencing similar problems.
