Question: What is the primary purpose of implementing packet filtering strategies on border gateways and access routers in IP-based networks, as per network domain security practices?
Option 1: To selectively allow key protocols (e.g., DNS, NTP) and specific tunnel mode traffic (IKEv2, IPsec ESP), while rejecting unsolicited traffic.
Option 2: To manage network bandwidth by limiting the amount of data that can be transmitted at any given time.
Option 3: To monitor all incoming and outgoing traffic for billing purposes.
Option 4: To bypass Security Gateway (SEG) functionality for certain types of traffic.
Explanation: The correct answer highlights the main objective of packet filtering in this context: to enhance security by selectively permitting essential protocols and specific secure tunnel mode traffic, while blocking unwanted, unsolicited traffic, aligning with Network Domain Security (NDS) principles.