IPA part of the fields in the message are specifically used to describe the life cycle of the message, namely TTL Value, what is its maximum value?

Question

Options

• A255
• B256
• C1023
• D1024

• A
  71% (30)
• B
  5% (2)
• C
  17% (7)
• D
  7% (3)

Explanation

Option A is correct because the TTL (Time to Live) field in an IP packet header is exactly 8 bits wide, and the maximum value an 8-bit unsigned integer can hold is 2^8 - 1 = 255. TTL is decremented by each router the packet passes through, and when it reaches zero the packet is discarded, preventing endless routing loops.

Option B (256) is wrong because 256 is the total count of possible values in an 8-bit field (0 through 255), not the maximum value itself. Options C (1023) and D (1024) are wrong because they would require a 10-bit field -- 1023 is 2^10 - 1 and 1024 is 2^10 -- neither of which matches the actual size of the TTL field.

Memory tip: 8-bit field, max value 255. Think of it as a single byte (8 bits), and the highest number one byte can store is always 255.

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