Due to customer interest and feedback on the upcoming enforcement of blocking domain fronting on existing Azure Front Door and Azure CDN Standard from Microsoft (classic), we are postponing domain fronting blocking enforcement to January 22, 2024, and will provide two log fields “SNI” and “Result” by December 25, 2023, to help customers in determining if the Azure Front Door and Azure CDN Standard from Microsoft (classic) resources display domain fronting behavior.
For more information on domain fronting, its impact on your Azure Front Door or Azure CDN from Microsoft resources, and how to verify the domain fronting block status on your resources, please refer to our blog. Please note that domain fronting block enforcement will not affect regular users who access the service through compliant browsers, API, SDK, etc. It will only prevent traffic that attempts to evade the domain fronting check by using mismatched SNI extension and HOST headers.