Huawei Certified ICT Associate – Data Center Network (HCIA-DCN) — Question 147

Which of the following statements are true about the TTL field in an IPv4 header? (Choose all that apply.)

Answer options

• A. The TTL field length is 8 bits.
• B. The TTL value decreases by 1 each time a packet passes through a Layer 3 device.
• C. When a routing loop occurs, the TTL value can be used to prevent infinite packet forwarding.
• D. The TTL value is in the range from 0 to 255.

Correct answer: B, C, D

Explanation

Option B is correct because the TTL value does indeed decrease by 1 with each Layer 3 device the packet encounters. Option C is also accurate as the TTL value helps prevent packets from being forwarded indefinitely in the case of routing loops. Option D is correct since the TTL value can range from 0 to 255. However, option A is incorrect because the TTL field is 8 bits long; it is actually 8 bits, but this is not a true statement by itself in the context of this question.