CCNA Practice Exam Test Sample – Question 90

Which IPv6 address is the equivalent of the IPv4 interface loopback address 127.0.0.1?

A. ::1
B. ::
C. 2000::/3
D. 0::/10

Correct Answer: A
Section: IP addressing (IPv4 / IPv6)

Explanation:
In IPv6 the loopback address is written as, ::1
This is a 128bit number, with the first 127 bits being ‘0’ and the 128th bit being ‘1’. It’s just a single address, so could also be written as ::1/128.