How to use Traceroute
The Traceroute tool maps the path that packets take from a source to a destination host, listing each router (hop) along the way and the latency to reach it. Where ping tells you only the round-trip time to the far end, traceroute reveals the whole journey, exposing exactly where a connection slows down or breaks. Use this tool to diagnose why a server feels distant, to pinpoint which network along the route is dropping packets or adding delay, and to understand the geography and providers your traffic crosses to get there.
- Enter the destination hostname or IP address.
- Click Trace to map the route hop by hop.
- Read each hop’s address and round-trip latency.
- Look for the hop where latency jumps or replies stop.
- Use the failing hop to localise the problem along the path.
How traceroute maps the path
Traceroute sends packets with a deliberately small time-to-live value that increases by one each round. The first packet expires at the first router, which reports back; the next expires at the second, and so on, so the replies trace out every hop between you and the destination. The latency to each hop shows where delay accumulates. A steady rise in latency across hops is normal as distance grows; a sudden large jump at one hop, sustained for the rest of the path, marks where a slow or congested link sits.
Reading stars and dead ends
Hops that show asterisks instead of times mean a router did not reply, which is often harmless: many routers deprioritise or block the diagnostic packets traceroute relies on, so a starred middle hop while later hops respond is nothing to worry about. What matters is where the trace stops completely. If replies cease partway and never resume, the problem likely lies at or just beyond the last responding hop. Identifying that point tells you which network — yours, an intermediate provider, or the destination’s — to investigate or report to.
| Observation | Likely meaning |
|---|---|
| Gradual latency rise | Normal distance increase |
| Sudden sustained jump | Congested or distant link |
| Asterisks then recovery | Router silently skips diagnostics |
| Trace stops entirely | Failure at or beyond last hop |
Glossary
- Traceroute
- A tool that maps the routers along the path to a destination.
- Hop
- A single router the packet passes through on its way.
- TTL
- Time to live — a counter that limits how many hops a packet can take.
- Round-trip time
- The latency to reach a hop and receive its reply.
- Asterisk hop
- A hop that did not reply, often because diagnostics are blocked.
Related reading
Frequently Asked Questions
Why use Traceroute?
- Map every router hop between the probe and a destination with per-hop latency
- Pinpoint the exact hop where a connection becomes slow or stops responding
- Identify the network providers and autonomous systems your traffic crosses
- See where geographic and provider boundaries introduce latency along a route
Common use cases
- Identify which ISP or exchange point adds latency on a slow international connection
- Diagnose where packet loss begins along a route to a cloud server experiencing timeouts
- Confirm that traffic to a CDN edge node takes an efficient regional path
- Investigate an intermittent timeout by locating the hop that sporadically fails
- Understand the network path between two data centres before planning a peering connection
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