Examkin

Question

Difficulty: EasyIPv6 Addressing and Prefixes

When an interface automatically constructs an IPv6 EUI-64 interface identifier using the MAC address 00:1A:2B:3C:4D:5E, which string represents the correctly generated 64-bit interface ID?

  1. 021a:2bff:fe3c:4d5eAnswer
  2. B
    001a:2bff:fe3c:4d5e
  3. C
    021a:2bff:ff3c:4d5e
  4. D
    021a:2b3c:4d5e:fffe

Answer

The correct interface identifier is 021a:2bff:fe3c:4d5e.
To create a 64-bit EUI-64 interface ID from a 48-bit MAC address, the 16-bit value FFFE is inserted between the third and fourth bytes of the MAC address. In addition, the 7th bit (universal/local bit) of the first byte must be inverted. Inverting the 7th bit of 0x00 results in 0x02, producing the complete interface ID 021a:2bff:fe3c:4d5e.

Step-by-Step Solution

1
Split the 48-bit MAC address into two 24-bit halves.
The left half is 00:1A:2B and the right half is 3C:4D:5E.
EUI-64 generation requires inserting a specific 16-bit hex value between the OUI and NIC specific bytes.
2
Insert the 16-bit hexadecimal value FFFE between the two halves.
The combined value becomes 00:1A:2B:FF:FE:3C:4D:5E.
FFFE expands the 48-bit MAC address into a 64-bit structure.
3
Invert the 7th bit (Universal/Local bit) of the first byte (00).
Hexadecimal 00 (0000 0000 in binary) becomes hexadecimal 02 (0000 0010 in binary).
IEEE EUI-64 rules require modifying the 7th bit to represent universal scope.
4
Format the resulting 64 bits into standard IPv6 colon-separated hextets.
021a:2bff:fe3c:4d5e
IPv6 interface identifiers are presented as four 16-bit hexadecimal hextets.

Key Concept

EUI-64 Interface ID Generation
Estimated Time:45s
Rate this question

Topics

IPv6 Addressing and Prefixes

More questions from this topic