Reading traceroute and mtr

traceroute shows each router between you and a destination. It's useful, but it's also the most misread tool in networking.

Use mtr instead

mtr runs traceroute continuously and shows loss and latency per hop:

mtr -rwc 100 yourcompany.com

Rule 1: loss in the middle is usually not loss

Routers deprioritise replying to traceroute. A hop showing 40% loss while later hops show 0% is not a problem; that router is simply busy with real traffic.

Real loss continues to the final hop.

Rule 2: look for the jump

Latency should rise in steps that match distance. A sudden jump that stays for all later hops shows where the delay begins. Cairo to Frankfurt adds around 50 – 60 ms; that's physics, not a fault.

Rule 3: the return path may differ

Traceroute shows the path to the destination. Replies may come back a different way, so ask for a trace from the other side too.

Asterisks

* * * means a hop didn't answer, often because of a firewall. If later hops respond, ignore it.