The network administrator is asked to configure 113 point-to-point links. Which IP addressing scheme best defines the address range and subnet mask that meet the requirement and waste the fewest subne

Question

Options

• A10.10.0.0/16 subnetted with mask 255.255.255.252
• B10.10.0.0/18 subnetted with mask 255.255.255.252
• C10.10.1.0/24 subnetted with mask 255.255.255.252
• D10.10.0.0/23 subnetted with mask 255.255.255.252
• E10.10.1.0/25 subnetted with mask 255.255.255.252

• A
  12% (5)
• B
  7% (3)
• C
  29% (12)
• D
  50% (21)
• E
  2% (1)

Explanation

Point-to-point links require exactly 2 usable host addresses, making a /30 subnet (255.255.255.252) ideal since it provides exactly 2 usable hosts per subnet. The question is which parent network provides just enough /30 subnets to cover 113 links without excessive waste. A /30 carves subnets from the parent by borrowing bits: a /23 parent yields 2^(30-23) = 2^7 = 128 subnets, which is the smallest power of 2 that exceeds 113. Options A (/16 = 16,384 subnets) and B (/18 = 4,096 subnets) provide far too many subnets. Option C (/24 = 64 subnets) and E (/25 = 32 subnets) are insufficient to cover 113 links. Therefore 10.10.0.0/23 subnetted with /30 gives exactly 128 subnets - just enough with minimal waste.

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