Which of the following is the multicast.mac address corresponding to the multicast address 224.0.1.1?

Question

Options

• A01-00-5e-00-01-00
• B01-00-5e-00-01-01
• C00-00-5e-00-01-1
• D00-00-5e-00-01-01

• A
  2% (1)
• B
  83% (34)
• C
  5% (2)
• D
  10% (4)

Explanation

Option B (01-00-5e-00-01-01) is correct because IPv4 multicast MACs are constructed by taking the fixed IANA prefix 01-00-5E, then mapping the low-order 23 bits of the multicast IP into the last three octets. For 224.0.1.1, those 23 bits yield 00-01-01, producing the full address 01-00-5E-00-01-01.

Why the distractors fail:

• A (…-00-01-00) uses the right prefix but gets the last octet wrong - the final .1 in the IP maps to 01, not 00.
• C & D (00-00-5e-…) use the wrong OUI prefix; 00-00-5E is IANA's unicast range, while multicast MACs must begin with 01-00-5E (the 01 in the first octet signals the multicast bit).

Memory tip: Think "0 1 = multicast 1" - the 01 at the start of the MAC is the key marker. Then just remember the IANA block 00-5E and map the last 23 bits of the IP straight across. If it starts with 00, it's unicast, not multicast - automatically wrong.

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