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How to Diagnose a Network Path with Traceroute

Follow these steps in order to trace and read a network path.

  1. What traceroute actually does

    Traceroute is a diagnostic tool that shows, one line at a time, every router your data passes through on its way from your computer to a destination server. It works by sending packets with a Time To Live (TTL) value that starts at 1 and increases by one each round; each router along the way discards the packet once its TTL hits zero and sends back an "ICMP Time Exceeded" message, and collecting those messages in order reveals the entire path.

  2. Run it on Windows (tracert)

    Open Command Prompt and type "tracert google.com" or "tracert 8.8.8.8". Windows uses ICMP packets, and the command is shortened to tracert instead of the full word traceroute.

  3. Run it on Mac and Linux (traceroute)

    Open Terminal and type "traceroute google.com". Mac and Linux send UDP packets by default, and confirm arrival at the destination when the target port is closed and returns an "ICMP Port Unreachable" response instead.

  4. How to read the results

    Each line represents one hop (a router along the path), showing its IP address or hostname along with three separate response time measurements. Higher hop numbers mean you are getting closer to the destination; domestic hops typically respond in the single digits to low tens of milliseconds, while response times noticeably jump once traffic crosses to an international segment.

  5. If response time suddenly jumps at one hop

    If the response time jumps sharply at a particular hop and stays roughly that high for every hop after it, that segment β€” often a backbone link or an undersea cable crossing β€” is genuinely where the delay is being introduced. But if only a single hop is slow and the next one speeds back up, that router most likely just deprioritizes ICMP replies, which usually is not a real problem.

  6. What the asterisks (* * *) mean

    When a hop shows asterisks instead of response times, it usually means that router is configured not to send ICMP or UDP replies at all for security reasons. This is extremely common and, as long as hops after the asterisks resume responding normally and traffic reaches the final destination, it is unlikely to indicate an actual connection problem.

If you just want the round-trip time

If you only care about the overall response time and packet loss to a destination rather than the full path, ping is the simpler tool to reach for first.

Narrowing down whether it is your problem or your ISP's

If the first one to three hops β€” your router and your ISP's access segment β€” look fine, but delay or no response shows up from there onward, the issue is more likely on your ISP's side or the destination server's side rather than your own network. If you want to rule out your router first, a simple router reboot is worth trying before anything else.

Frequently Asked Questions

If I see * * * does that mean my internet is down?

No. Many routers are configured, for security reasons, not to send ICMP or UDP replies at all, so seeing asterisks is very common. If the hops after the asterisks respond normally again and the trace reaches its final destination, there is usually no actual problem.

Do tracert and traceroute work exactly the same way, just with different names?

They share the same goal but differ under the hood. Windows' tracert uses ICMP packets, while Mac and Linux's traceroute uses UDP packets by default to trace the path, which is why the same destination can occasionally produce slightly different results on the two operating systems.