An organization is granted the block 130.56.0.0/16. The administrator wants to…

2022

An organization is granted the block 130.56.0.0/16. The administrator wants to create 1024 subnets. .

Find first and last addresses of last subnet.

  1. A.

    130.56.0.0    130.56.254.255

  2. B.

    130.56.255.0    130.56.255.255

  3. C.

    130.56.0.192    130.255.255.255

  4. D.

    130.56.255.192    130.56.255.255

Attempted by 176 students.

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Correct answer: D

Final answer: 130.56.255.192 to 130.56.255.255

  1. Start with the given block: 130.56.0.0/16. You need 1024 subnets.

  2. Since 1024 = 2^10, you must borrow 10 bits from the host portion.

  3. New prefix length = 16 + 10 = /26.

  4. Addresses per subnet = 2^(32 - 26) = 64 addresses (62 usable hosts).

  5. Subnets increment by 64 in the last octet. The last subnet index is 1023, so offset = 1023 × 64 = 65472, which corresponds to .255.192 in the last two octets.

  6. Therefore the last subnet's network address = 130.56.255.192 and its broadcast (last address) = 130.56.255.255.

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