Cisco Certified Network Associate (CCNA) Practice Exam 2025 - Free CCNA Practice Questions and Study Guide

Tunnel Mode offers greater security by encapsulating the entire IP packet, which includes the original IP header and the payload. This is particularly important in Virtual Private Networks (VPNs) where the encapsulation process helps to protect the integrity and confidentiality of the data being transmitted. When the data is encapsulated, it is not only encrypted but also given a new IP header, thus masking the original source and destination addresses. This added layer of security is essential for protecting sensitive information as it travels across untrusted networks like the Internet.

Other modes, such as Transport Mode, only encrypt the payload of the IP packet and leave the original IP header intact, which does not provide the same level of security since the original addresses remain visible and could be exploited. Secure Mode is not a standard term recognized within common networking practices and may not pertain to a specific encapsulation strategy, making it irrelevant in this context. As such, Tunnel Mode is the most effective choice for enhancing security through the comprehensive encapsulation of the entire IP packet.