Which IP addresses belong to class A? (Select two.)

Question

Options

• A15.196.68.4
• B126.99.29.199
• C155.169.90.45
• D199.87.11.49

• A
  77% (27)
• C
  6% (2)
• D
  17% (6)

Explanation

Class A addresses use a first octet range of 1–126, which both options A (15.x.x.x) and B (126.x.x.x) satisfy - making them the correct answers.

C is wrong because 155.x.x.x falls in the Class B range (first octet 128–191). D is wrong because 199.x.x.x falls in the Class C range (first octet 192–223). Note that 127.x.x.x is reserved for loopback and is excluded from Class A, which is why 126 is still valid but 127 is not.

Memory tip: Think of the classes as blocks - A ends at 126, B runs 128–191, C runs 192–223. A quick way to remember: "A is low (1–126), B is mid (128–191), C is high (192–223)." Just check the first octet and you'll classify any address instantly.

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