Which functions require Apple devices to continuously access APNs?

Apple Push Notification service (APNs) is a critical service that Apple devices rely on for real-time notifications. Functions requiring continuous APNs access include notifications for operating-system and app updates, MDM policy enforcement (e.g., remote commands), and incoming messages (e.g., iMessage). These depend on APNs to push data to devices over ports 5223 or 443. Options A (Bonjour, caching, sharing), B (SSO, VPN, roaming), and D (tracking, backups, suggestions) involve other mechanisms like local networking or iCloud, not continuous APNs access. TheApple Platform Deployment Guidedetails APNs’ role in these functions.