What Is the Traceroute Command?
Understand how traceroute maps the path to a destination, how to read its output, and platform-specific variations.
Traceroute Basics
Traceroute discovers the path packets take to a destination by sending probes with gradually increasing time-to-live (TTL) values. Each router along the way decrements the TTL and, when it reaches zero, returns an ICMP message that reveals its address.
By recording the routers that respond, traceroute builds a hop-by-hop map of the route from your device to the target host. This is extremely useful for pinpointing where latency, packet loss, or routing loops occur.
tracert is the traceroute equivalent on Windows.
tracert www.example.com
tracert 8.8.8.8
Run these in Terminal to trace network paths.
traceroute www.example.com
traceroute 8.8.8.8
Reading Traceroute Output
Each line of traceroute output represents one hop, showing the router’s address and round-trip time for several probes. Asterisks indicate timeouts, which can mean a firewall is blocking ICMP responses or that a router is deprioritizing them.
Look for sudden jumps in latency or long runs of timeouts. Those often point to congestion or filtering on a specific link. While traceroute cannot fix issues by itself, it gives you evidence to share with your ISP or network administrator.