An ACL rule is rule 5 permit ip source 10.1.0.255 0.254.255 Which of the following IP addresses can be matched by the permit rule? (Multiple choice)

Question

Options

• A10.1.1.1
• B6.1.3.1
• C7.1.3.1
• D10.2.2.1

• A
  79% (22)
• C
  7% (2)
• D
  14% (4)

Explanation

The wildcard mask 254.0.255.255 (where 254 = binary 11111110) means only the least significant bit of the first octet must match the source - since source octet 1 is 10 (binary 00001010, LSB = 0), any address with an even first octet satisfies this; the second octet wildcard 0 means it must equal 1 exactly; octets 3–4 (255) are unconstrained. A (10.1.1.1) matches because 10 is even and the second octet is 1; B (6.1.3.1) also matches because 6 is even (00000110, LSB = 0) and the second octet is 1. C (7.1.3.1) fails because 7 is odd (00000111, LSB = 1), violating the first-octet constraint. D (10.2.2.1) fails because its second octet is 2, not 1 (the wildcard 0 requires an exact match there).

Memory tip: Convert the wildcard octet to binary - every 1 bit is a "don't care" bit, every 0 bit is a "must match" bit. A wildcard of 254 (11111110) locks only the LSB, so it splits addresses into even (matches) vs. odd (fails). Always check each octet independently.

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