For more than a decade, Microsoft has been sharing Advance Notification Service (ANS) as part of Patch Tuesday program in order to communicate in advance, about the security updates being released for Microsoft products and services each month. Due to change in the technology environments and customer needs have evolved, Microsoft is now changing the way they share share this information. Going forward, Microsoft will provide ANS information directly to Premier customers and current organizations involved in our security programs, and will no longer make this information broadly available on the web.
ANS has always been optimized for large organizations. However, customer feedback indicates that many of our large customers no longer use ANS in the same way they did in the past due to optimized testing and deployment methodologies. While some customers still rely on ANS, the vast majority wait for Update Tuesday, or take no action, allowing updates to occur automatically. More and more customers today are seeking to cut through the clutter and obtain security information tailored to their organizations. Rather than using ANS to help plan security update deployments, customers are increasingly turning to Microsoft Update and security update management tools such as Windows Server Update Service to help organize and prioritize deployment. Customers are also moving to cloud-based systems, which provide continuous updating.
Read more about it from the link below.