Traceroute is the tool that shows the path between two points on the internet, router by router. It is the first thing a technician asks for when a website is slow or unreachable for only some people. The output looks like a confusing list of numbers, but reading it is simpler than it seems.
What each line means
Each line is a hop: a router the packets passed through. For each hop you see:
- The hop number: 1 is the first router (at home, usually your own router), and the numbers go up until the destination.
- The router's IP or name: many ISP router names include the city, such as
sao,gru,rjoormia. - The time: how long that router took to reply, round trip, in milliseconds.
Annotated example
| 1 | 192.168.0.1 — 1 ms (your router) |
|---|---|
| 2 | 100.64.0.1 — 6 ms (ISP, CGNAT range) |
| 3 | * no reply (router that does not answer the test) |
| 4 | be-1.sao.operadora.net — 9 ms (São Paulo) |
| 5 | mia.backbone.net — 118 ms (left Brazil: the time jumps) |
| 6 | destination — 120 ms |
How to read it: everything is normal up to São Paulo, then the time jumps to 118 ms at hop 5 because the path crossed over to Miami. From there, the time holds steady. If the destination were a Brazilian website, that detour through the United States would explain the slowness.
The three golden rules
1. Look at the trend, not a single hop
If a hop in the middle shows 200 ms and the following ones drop back to 20 ms, that router was just slow to answer the test (this is common: replying to traceroute is low priority for routers). The real traffic went through quickly. The real problem shows up when the time rises and stays high on every hop after it.
2. Asterisks are not always a problem
An occasional "no reply" hop in the middle is normal: many routers are configured not to respond. Only worry if the replies stop for good and nothing else answers all the way to the end, including the destination. That means something from that point on is blocking traffic or is down. Also keep in mind that many servers block the test with a firewall, so the destination may not reply even when it is working: confirm with Is the site down?
3. Physical distance matters
Every thousand kilometers (about 620 miles) of fiber adds roughly 10 ms round trip. A hop that crosses an ocean naturally adds 60 ms or more. That is not a fault, it is physics.
Commands to run on your computer
- Windows:
tracert example.com - macOS:
traceroute example.com - Linux:
traceroute example.comortracepath example.com
TestePing's online traceroute runs from our server in Miami. It is useful for comparison: if the route from there looks good and yours looks bad, the problem is between you and your ISP.
How to use the result with your ISP
When you open a ticket about slowness, send a traceroute from your computer to the destination, taken while the problem is happening, along with a ping test. Point out the hop where the time spikes. That shortens the support process a lot.