Question: In an NB-IoT network, after a UE (User Equipment) sends an `AttachRequest` to the NB-SS (Narrowband-SS), what security-related action does the NB-SS initiate before sending `AttachAccept` to the UE?
Option 1: The NB-SS updates the UE's TAI (Tracking Area Identity) without any additional security measures.
Option 2: The NB-SS initiates authentication and starts integrity protection using a security procedure.
Option 3: The NB-SS sends a new temporary GUTI (Globally Unique Temporary Identifier) without initiating any security protocols.
Option 4: The NB-SS skips security procedures for initial attachments in NB-IoT networks.
Explanation: In the context of secure telecommunications, especially in low-bandwidth, high-efficiency networks like NB-IoT, maintaining the integrity and confidentiality of data is crucial. After receiving an `AttachRequest`, initiating authentication ensures the UE's identity is verified, and starting integrity protection (typically via encryption) safeguards subsequent communications. This dual approach is standard in secure network attachments to prevent unauthorized access and ensure data integrity, aligning with the principles of secure communication protocols in telecom networks.