CISCO CCNA Exam – Q135

Which option is a valid IPv6 address?

A. 2001:0000:130F::099a::12a
B. 2002:7654:A1AD:61:81AF:CCC1
C. FEC0:ABCD:WXYZ:0067::2A4
D. 2004:1:25A4:886F::1

Correct Answer: D

Explanation:
An IPv6 address is represented as eight groups of four hexadecimal digits, each group representing 16 bits (two octets). The groups are separated by colons (:). An example of an IPv6 address is 2001:0db8:85a3:0000:0000:8a2e:0370:7334. The leading 0’s in a group can be collapsed using ::, but this can only be done once in an IP address.

CISCO CCNA Exam – Q97

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

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.