200-101 · Question #174
Identify the four valid IPv6 addresses. (Choose four.)
The correct answer is A. :: B. ::192.168:0:1 E. 2002:c0a8:101::42 F. 2003:dead:beef:4dad:23:46:bb:101. Valid IPv6 addresses use only hexadecimal groups separated by colons, with '::' used at most once to compress consecutive all-zero groups. Addresses that represent network prefixes or contain invalid group notation are not valid host addresses.
Question
Exhibit
Options
- A::
- B::192.168:0:1
- C2000::
- D2001:3452:4952:2837::
- E2002:c0a8:101::42
- F2003:dead:beef:4dad:23:46:bb:101
How the community answered
(36 responses)- A81% (29)
- C6% (2)
- D14% (5)
Why each option
Valid IPv6 addresses use only hexadecimal groups separated by colons, with '::' used at most once to compress consecutive all-zero groups. Addresses that represent network prefixes or contain invalid group notation are not valid host addresses.
:: is the IPv6 unspecified address, representing all 128 bits as zero (equivalent to 0:0:0:0:0:0:0:0), and is a valid reserved IPv6 address defined in RFC 4291.
::192.168:0:1 is a valid IPv4-compatible IPv6 address where the low-order bits encode an IPv4 address, a format recognized in IPv6 transition mechanisms.
2000:: represents the first address of the Global Unicast range and functions as a network prefix identifier rather than an assignable host address.
2001:3452:4952:2837:: compresses the lower 64 bits to all zeros with the trailing ::, making it a subnet prefix address rather than a valid assignable host address.
2002:c0a8:101::42 is a valid 6to4 address where c0a8:0101 is the hexadecimal encoding of IPv4 address 192.168.1.1, and :: correctly compresses consecutive zero groups.
2003:dead:beef:4dad:23:46:bb:101 is a valid full-form IPv6 address with all eight 16-bit hexadecimal groups explicitly stated using legal hex values.
Concept tested: Valid IPv6 address notation and host address identification
Source: https://www.cisco.com/c/en/us/support/docs/ip/ip-version-6/113328-ipv6-address-format.html
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