traceroute Command Reference: Flags, Usage & CI Examples

traceroute maps the network path and per-hop latency to a host.

traceroute shows the sequence of routers between the runner and a destination, with latency per hop. It is a diagnostic for where connectivity breaks down, not a routine check.

Common flags and usage

-n: numeric output, skip reverse DNS (faster)
-m <hops>: maximum number of hops
-w <secs>: per-hop wait timeout
-T: use TCP SYN probes (better through firewalls)
-p <port>: destination port for TCP probes

Example

shell

traceroute -n -m 20 -w 2 api.example.com

In CI

Reach for traceroute when a job intermittently cannot reach a host and you need to see where the path stalls. Use -n to skip slow reverse-DNS and -T for TCP probes, since intermediate hops often drop the default UDP/ICMP packets.

Key takeaways

traceroute reveals the per-hop path and latency to a host.
It is a diagnostic for flaky connectivity, not a routine gate.
-n speeds it up; -T traces better through firewalls.

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