Question: In a GPRS network, what is the primary purpose of constructing the full Access Point Name (APN) during PDP context activation?
Option 1: To authenticate User Equipment (UE) with the Serving GPRS Support Node (SGSN)
Option 2: To interrogate the Domain Name System (DNS) server for obtaining the P-GW/GGSN address
Option 3: To select the appropriate Quality of Service (QoS) profile for the UE
Option 4: To encrypt data transmissions between the UE and the SGSN
Explanation: The full APN, combining Network Identifier (APN-NI) and Operator Identifier (APN-OI), is crucial for resolving the P-GW/GGSN's IP address via DNS queries. This process establishes the correct data transmission path between the GPRS network and external packet data networks.