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N10-005 · Question #593

Which of the following is an invalid MAC address?

The correct answer is C. 56:AD:BX:89:55:54. A valid MAC address consists of exactly 12 hexadecimal characters (0-9 and A-F); the address containing 'X' is invalid because X is not a hexadecimal digit.

Networking concepts

Question

Which of the following is an invalid MAC address?

Options

  • AAA:CE:58:FD:90:08
  • B44:98:3E:F8:33:23
  • C56:AD:BX:89:55:54
  • D94:9E:FE:EE:8C:DF

How the community answered

(60 responses)
  • A
    2% (1)
  • B
    2% (1)
  • C
    90% (54)
  • D
    7% (4)

Why each option

A valid MAC address consists of exactly 12 hexadecimal characters (0-9 and A-F); the address containing 'X' is invalid because X is not a hexadecimal digit.

AAA:CE:58:FD:90:08

AA:CE:58:FD:90:08 contains only valid hexadecimal characters (0-9, A-F) in the correct 6-octet colon-delimited format.

B44:98:3E:F8:33:23

44:98:3E:F8:33:23 is a properly formed MAC address using only valid hexadecimal digits.

C56:AD:BX:89:55:54Correct

The address 56:AD:BX:89:55:54 contains the character 'X' in the third octet, which is not a valid hexadecimal digit. Hexadecimal uses only the digits 0-9 and the letters A-F. The presence of any character outside this set makes the address syntactically invalid and impossible to assign to a real network interface.

D94:9E:FE:EE:8C:DF

94:9E:FE:EE:8C:DF uses only valid hexadecimal characters and follows the correct MAC address format.

Concept tested: Valid hexadecimal MAC address format

Source: https://standards.ieee.org/develop/regauth/tut/eui48.pdf

Topics

#MAC address#hexadecimal#addressing#invalid address

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