Cisco Certified Network Associate (CCNA) Practice Exam

Which three of the following are IPv6 transition mechanisms?

1. 6to4 tunneling

2. GRE tunneling

3. ISATAP tunneling

4. Teredo tunneling

The correct answer is: 6to4 tunneling

The correct answer includes multiple options that are valid IPv6 transition mechanisms. In the context of transitioning from IPv4 to IPv6, understanding these mechanisms is crucial because they facilitate communication between the two protocols. 6to4 tunneling allows you to encapsulate IPv6 packets within IPv4 packets, enabling IPv6 connectivity over an IPv4 network without the need for explicit tunnels. It utilizes a special IPv6 addressing format based on the IPv4 address, allowing for a simple and automatic method of tunnel creation. ISATAP (Intra-Site Automatic Tunnel Addressing Protocol) is another tunneling method that enables IPv6 packets to be transmitted within an IPv4 network using automatic tunneling. It is particularly useful for transitioning within enterprise networks. Teredo tunneling allows IPv6 connectivity even when the host is behind a NAT (Network Address Translation) device, which is common in many residential and corporate environments. It provides a mechanism for users to access IPv6 without changing their underlying IPv4 network configuration. These mechanisms are all important in facilitating the gradual adoption of IPv6. Each serves a specific purpose in different networking scenarios, helping to ensure that communication remains functional during the transition period from IPv4 to IPv6.