CompTIA Network+ Practice Test

What is the primary function of IPsec in the OSI model?

1. Authentication and encryption for every packet

2. Packet filtering at the application layer

3. Data compression for faster transmission

4. Routing decision based on policies

The correct answer is: Authentication and encryption for every packet

The primary function of IPsec in the OSI model is to provide authentication and encryption for every packet. This security protocol suite operates primarily at the network layer, allowing for the secure transmission of data between devices over an IP network. IPsec ensures that data is not only protected against eavesdropping through encryption but also verifies the identity of the sender and the integrity of the data being transmitted through various authentication methods. This capability is crucial for establishing secure Virtual Private Networks (VPNs) and is essential for maintaining the confidentiality and integrity of sensitive information being exchanged over potentially insecure networks. The other choices, while related to network operations, do not accurately represent the primary function of IPsec. Packet filtering is more associated with firewalls and occurs at the network layer, but it does not encompass the broader security provisions that IPsec offers. Data compression is a different operation that is concerned with reducing the size of the data being sent, which is not the focus of IPsec. Routing decisions are typically made based on routing protocols and administrative policies and do not directly relate to the security functions provided by IPsec. Therefore, the correct understanding of IPsec's primary function focuses on its capabilities for authentication and encryption in the context of secured IP communications.