Question: During IMS Registration, if the new and previously assigned S-CSCF names differ in a command other than Multimedia-Auth-Request, what action does the HSS take if the S-CSCF reassignment pending flag is not set?
Option 1: Overwrite the S-CSCF name with the new one.
Option 2: Send a response to the S-CSCF indicating an error and do not overwrite the S-CSCF name.
Option 3: Trigger a synchronisation failure procedure, requesting an auts parameter for verification.
Option 4: Ignore the command and maintain the existing S-CSCF assignment without notification.
Explanation: According to error handling during IMS registration, if new and previously assigned S-CSCF names differ (excluding Multimedia-Auth-Request) and the reassignment pending flag is not set, the HSS responds with an error to the S-CSCF without overwriting the existing name, ensuring consistency and preventing unauthorized changes.