Question: In a 5G System, when the Network Exposure Function (NEF) receives updated DNAI Mapping information from the Unified Data Repository (UDR), how does it notify a previously subscribed Application Function (AF)?
Option 1: By sending an HTTP POST request message to the AF with the DnaiMapUpdateNotif data structure.
Option 2: Through a direct database update, ensuring the AF polls for changes periodically.
Option 3: Utilizing SMS notifications to inform the AF of the update, which then fetches details from the NEF.
Option 4: By initiating a new subscription process for the updated DNAI Mapping information with the AF.
Explanation: This is correct because, according to the specified procedure, when the NEF receives an update on DNAI Mapping information from the UDR, it proactively notifies subscribed AFs by sending an HTTP POST request. This method ensures timely updates and aligns with the API-based interaction model typical in 5G system architectures for efficient network exposure and application service enablement. The use of HTTP POST for notifications is a standard approach in web-based APIs for pushing updates to interested parties, fitting the context of Northbound APIs in telecom networks.