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SESK: Stuff Everyone Should Know · sesk.info/tech-traceroute-incrementing-ttl

How does traceroute reveal successive routers along a path?

It sends probes with incrementing TTL values.

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  1. By changing the source MAC vendor
  2. By lowering the DNS cache time
  3. By incrementing probe TTL values ✔

Why: Traceroute begins with a small IP time to live and increases it for later probes. Each router decrements TTL, and the router where it reaches zero can return an ICMP Time Exceeded message.

Huh, didn't know that: TTL is a hop limit in this use, even though its name says time.

The dad joke
Traceroute counted every hop but never needed a pogo stick.
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References

Answer: By incrementing probe TTL values. Traceroute begins with a small IP time to live and increases it for later probes. Each router decrements TTL, and the router where it reaches zero can return an ICMP Time Exceeded message.

  1. Cloudflare: What is My Traceroute (MTR)? www.cloudflare.com/learning/network-layer/what-is-mtr
    increments the TTL, and sends new packets
    Checked 2026-10-11.

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