What is the IPv6 prefix of the address 2001:00cb:1562:0dc3:5400:0001:24a0:0014 if the prefix length is /56?

A) 2001:00cb:1562:0dc3:5:
B) 2001:00cb:1562:
C) 2001:00cb:1562:0dc:
D) 2001:00cb:1562:0d:

D
Explanation: D) When you are calculating the IPv6 prefix, it is useful to note that each hex digit is worth 4 binary digits; that is, add one extra hex digit and you add 4 bits to the prefix. In this case, the prefix used was 8 bits less than 64 (which is half way and easy to separate); this means removing two hex digits (8 bits).