Cisco Certified Network Associate (CCNA) Practice Exam

What type of IPv6 tunneling enables IPv6 to be tunneled via IPv4?

1. 6to4 tunneling

2. ISATAP tunneling

3. GRE tunneling

4. Teredo tunneling

The correct answer is: 6to4 tunneling

6to4 tunneling is a method that allows IPv6 packets to be transmitted over an IPv4 network. It works by encapsulating IPv6 packets within IPv4 headers, which facilitates communication between IPv6 nodes across an IPv4 infrastructure without requiring explicit tunneling configuration. Essentially, 6to4 utilizes a special IPv6 address format that allows automatic tunneling and is suited for scenarios where a direct IPv6 connection isn't available. This method operates by using a set of well-defined IPv6 address ranges that include an embedded IPv4 address, thus making it possible for the IPv6 network to identify the relevant IPv4 path for the transit of the data. By leveraging the existing IPv4 infrastructure, 6to4 simplifies the migration to IPv6 as it can facilitate IPv6 traffic over IPv4 networks seamlessly. The other tunneling methods mentioned, while they also support IPv6 transport, utilize different mechanisms and are appropriate for different scenarios. For instance, ISATAP is designed for intranet environments, GRE can encapsulate any Layer 3 protocol over an IP network (not specifically tailored for IPv6), and Teredo provides tunneling for IPv6 in scenarios where NAT (Network Address Translation) is present. This makes 6to4 the