Cisco Certified Network Associate (CCNA) Practice Exam

Which of the following statements is true regarding IPv6 addresses?

1. Every interface cannot have multiple IPv6 addresses

2. Leading zeros in an IPv6 hexadecimal field can be omitted

3. The 128-bit address structure is divided into segments of six bits each

4. Every IPv6 interface contains at least one loopback address

The correct answer is: Every IPv6 interface contains at least one loopback address

The statement that every IPv6 interface contains at least one loopback address is accurate. In IPv6, the loopback address is defined as ::1, which is the equivalent of the IPv4 loopback address 127.0.0.1. This address allows a device to send and receive packets to itself, facilitating testing and troubleshooting network configurations. Every IPv6-enabled device or interface automatically has this loopback address for internal communications, serving an essential role in the functioning of the network stack. In contrast, the other statements do not hold true. For instance, interfaces can indeed have multiple IPv6 addresses, allowing for the assignment of different types of addresses (such as global, link-local, etc.) to the same interface. Additionally, while leading zeros in an IPv6 address can be omitted for simplicity, this does not apply to entire fields; thus, there is some nuance in how address formatting is applied. Lastly, the structure of an IPv6 address is not divided into six-bit segments, but rather into 16-bit segments, which complicates the division of the address into those smaller parts incorrectly.