@font-face EOT Not Loading over HTTPS: A Resolution

In an encounter with a problem where @font-face EOT files failed to load over HTTPS in Internet Explorer versions 7, 8, and 9, a user observed that the issue persisted regardless of the hosting status of the containing HTML page on HTTPS. Upon experimentation, the user discovered that the font loaded successfully when accessed via HTTP but not HTTPS.

After ruling out font-specific issues and confirming that the server hosting the font provided the appropriate content-type for EOT files, the user sought assistance to resolve the problem.

In response, a solution was provided that addressed a critical aspect often overlooked when accessing resources over HTTPS. It was discovered that the presence of a Cache-Control header with a "no-cache" directive for the font caused Internet Explorer to ignore the downloaded font, leading to the observed behavior.

This finding aligns with Microsoft's documented behavior, where IE ignores downloaded active documents over SSL when a Cache-Control header specifies "no-cache." Therefore, it is recommended to remove the Cache-Control header to resolve this issue and ensure proper font loading over HTTPS in Internet Explorer.