@Tomohiko Hirahara Thank you for reaching out to Microsoft Q&A. I understand that you want to know if traffic for Windows updates can be routed via Azure Peering Service. Peering service supports All Microsoft public cloud traffic. However, Windows updates are sometimes served via 3rd party CDN also. So we cannot determine the exact route that it may take due to this. Hope this helps.
Please let us know if you have any further questions/concerns and we will be glad to assist further. Thank you!
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