What happens to a packet when TTL reaches 0?
22maya2n2 · posted · 38 views
I know TTL decrements at each hop but what exactly happens when it hits zero? Does the packet just disappear? Does the router send something back? And how does this relate to traceroute? I've seen TTL mentioned in ping output but never really understood the mechanics.
- The router drops the packet and sends back an ICMP Time Exceeded message to the source. That's literally how traceroute works — it sends packets with TTL 1, then 2, then 3, and so on. Each router along the path sends back a Time Exceeded reply, revealing its IP address. Pretty clever. — NivSa,
- That traceroute explanation just clicked for me. So each router reveals itself by sending back the Time Exceeded. Brilliant design honestly. I ran a traceroute in the lab and now I can actually read the output. Appreciate it. — 22maya2n2,
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