D is for dizzy

Which of these would be a valid IPv6 address?

A) fe80::5d18::652:cffd:8f52

B) fe80::2231:7:a:8:2

C) fe80::230:h812:11:19

D) fe80:0000:0000:0000:5d18:0652:cffd:8f52:23ff

E) Put together any jumble of letters and numbers

The answer: B) fe80::2231:7:a:8:2

IPv6 addresses are summarized by collapsing the zero fields with one set of double colons. Another shortcut is dropping the leading zeros in a group. An IPv6 address consists of eight groups, with two bytes in each group.

The first answer, A) fe80::5d18::652:cffd:8f52, is not correct because of the use of two colon abbreviations. You can only use a single set of double-colons in an IPv6 address to designate a series of zero groups.

Answer C) would not be the correct answer because the value h is not used in hexadecimal. Hexadecimal characters would be the values 0 through 9, and a through f.
Answer D) is properly formatted, but the size of the address is two bytes too large.

Answer B) is the correct answer, and the unabbreviated IPv6 address would be fe80:0000:0000:2231:0007:000a:0008:0002.

Want to know more? Watch “IPv4 and IPv6.”

Although IPv4 has been the most popular protocol in the world, IPv6 has now become a standard installation in Windows 7. In this video, you’ll learn how to identify IPv4 addresses and IPv6 addresses, and how IPv6 addresses can be abbreviated to save space and make them more readable.