Question: In a Cellular Network, what is the primary purpose of the "Unknown Tracking Area List" Information Element (IE) in E-UTRAN and NG-RAN?
Option 1: To identify cells with poor coverage for future network optimization.
Option 2: To list all available Tracking Areas (TAs) for roaming subscribers.
Option 3: To specify Tracking Areas unknown to the MME/AMF where a Cell Broadcast Service (CBS) Request cannot be delivered.
Option 4: To manage handover procedures between different Radio Access Technologies (RATs).
Explanation: The correct answer, Option 3, highlights the key function of the "Unknown Tracking Area List" IE, which is to identify those Tracking Areas that are not recognized by the Mobility Management Entity/Access and Mobility Management Function (MME/AMF), thereby indicating where a CBS Request cannot be successfully delivered. This is crucial for efficient network operation and service delivery in E-UTRAN (Evolved Universal Terrestrial Radio Access Network) and NG-RAN (Next Generation Radio Access Network).