Huawei Certified Network Associate – Routing and Switching (HCNA-RS, legacy) — Question 126

Which of the following statements are correct about TTL field in IP packet? (Choose two)

Answer options

• A. The maximum value of TTL is 65535.
• B. Normally, it's impossible for a router to receive a packet whose TTL is zero.
• C. The main purpose of TTL is to prevent IP packets from circulating endlessly in a network which can consume a lot of bandwidth.
• D. TTL value will be decremented as a packet is passed through the network devices such as hub, LAN switch and router.

Correct answer: B, C

Explanation

Option B is correct because routers drop packets with a TTL of zero to prevent them from being forwarded. Option C is also correct as TTL is designed to limit the lifespan of packets in the network. Options A and D are incorrect; the maximum TTL value is actually 255, and TTL is only decremented by routers, not by hubs or switches.