# Use Traceroute to Diagnose Network Issues Traceroute maps the sequence of gateways a packet crosses on its way from your PBX to a destination host. Because it shows each router along the path and how long each hop takes, it is a fast way to confirm that a host is reachable and to pinpoint where a connection is stalling or dropping. The tool is built into the web portal, so you can run it directly from the PBX. ## Run a traceroute 1. Sign in to the PBX web portal and go to **Maintenance > Troubleshooting > Traceroute**. 2. In the **Target Host** field, type the domain name or IP address you want to reach. 3. Click **Start**. The PBX begins tracing the route to the target. 4. Let the trace finish on its own, or click **Stop** to end it early. It also stops automatically once it reaches the destination or the maximum hop count. ## Interpret the results The trace opens with two summary lines before the per-hop detail begins. The first line, `start...`, simply marks the start of the run. The second line names the target you entered, the IP address it resolved to, the maximum number of hops the trace will attempt (30), and the size of each probe packet (46 bytes). Every line after that describes one hop and follows this pattern: ``` HOP Domain Name (IP Address) RTT1 RTT2 RTT3 ``` - **HOP**: Every time a packet is handed off between routers, that step counts as one hop. The hop number at the far right of the trace (before it reaches the target) tells you how many routers separate the PBX from the destination. - **Domain Name (IP Address)**: The router at that hop. When a reverse DNS name is available it appears alongside the IP and often hints at the router's location; otherwise only the IP address is shown. - **RTT1, RTT2, RTT3**: The round-trip time (RTT), in milliseconds, for a packet to reach that hop and return. This is the same latency figure you get from ping. Traceroute probes each hop three times so you can gauge how steady the latency is. An asterisk (`*`) in place of a time means no reply was received for that probe, which can point to packet loss. :::note A router showing `* * *` has not answered the traceroute probes, but that does not always mean a problem. Many routers are configured to forward traffic while ignoring these requests, so a hop can appear unresponsive and still pass packets to the next hop. ::: ### Example 1: A healthy path In the trace below, the destination is reached and round-trip times stay reasonable throughout. Several early hops answer with `* * *` yet still forward traffic to the next router, so the path is intact. ``` start... traceroute to www.example.com (36.152.44.95), 30 hops max, 46 byte packets 1 * * * 2 * * * 3 192.168.1.1 (192.168.1.1) 1.853 ms 11.642 ms 19.951 ms 4 110.80.36.161 (110.80.36.161) 3.008 ms 2.966 ms 3.943 ms 5 61.154.238.133 (61.154.238.133) 7.369 ms 27.982 ms 7.808 ms 6 117.30.27.177 (117.30.27.177) 6.125 ms 117.30.24.213 (117.30.24.213) 4.664 ms 4.376 ms 7 202.97.36.117 (202.97.36.117) 26.446 ms 202.97.64.178 (202.97.64.178) 22.534 ms 202.97.79.33 (202.97.79.33) 20.897 ms 8 202.97.63.18 (202.97.63.18) 33.276 ms 202.97.76.238 (202.97.76.238) 36.685 ms 202.97.18.46 (202.97.18.46) 33.961 ms 9 * * * 10 * * * 11 * * * 12 * * * 13 * * * 14 221.183.14.14 (221.183.14.14) 40.599 ms 221.183.18.2 (221.183.18.2) 54.233 ms 15 183.207.22.21 (183.207.22.21) 43.056 ms 53.602 ms 50.481 ms 16 183.207.23.122 (183.207.23.122) 47.251 ms 183.207.23.126 (183.207.23.126) 47.401 ms 183.207.23.110 (183.207.23.110) 54.380 ms 17 * * * 18 * * * 19 * * * 20 * * * 21 * * * 22 * * * 23 202.97.23.149 (202.97.23.149) 14.133 ms * 202.97.23.157 (202.97.23.157) 28.851 ms 24 61.154.238.69 (61.154.238.69) 7.096 ms 117.30.24.213 (117.30.24.213) 4.682 ms 117.30.27.189 (117.30.27.189) 2.758 ms 25 113.96.4.170 (113.96.4.170) 14.663 ms 113.96.5.118 (113.96.5.118) 17.857 ms 113.96.4.190 (113.96.4.190) 20.665 ms 26 * * * 27 * * * 28 * * * 29 110.80.36.161 (110.80.36.161) 4.278 ms 2.696 ms 3.900 ms 30 61.154.238.133 (61.154.238.133) 11.424 ms 4.690 ms 7.770 ms ``` ### Example 2: A path that breaks off Here the trace resolves the target and answers cleanly through hop 10, then returns `* * *` for every hop from 11 onward until it hits the 30-hop limit. When responses stop at one point and never resume, the connection is failing somewhere past the last hop that replied, so that is where to focus your investigation. :::caution A trace that shows `* * *` for every remaining hop up to the 30-hop limit does not always mean the host is unreachable. Many destination servers and firewalls silently drop traceroute probes for security while still accepting real traffic such as SIP (the protocol that carries calls) or HTTPS. Before you conclude the path is down, confirm the outage another way, for example by testing the actual service. ::: :::tip When a trace fails, look at the last hop that answered. If its address is a private one (for example `192.168.x.x`, `10.x.x.x`, or `172.16.x.x` through `172.31.x.x`), the break is inside your own network and is yours to fix. If the last good hop is a public address, the fault is upstream at your internet provider or a carrier along the route, and you will likely need to open a ticket with them. ::: ``` start... traceroute to www.example.com (14.215.177.38), 30 hops max, 46 byte packets 1 * * * 2 * * * 3 192.168.1.1 (192.168.1.1) 1.702 ms 4.912 ms 1.873 ms 4 110.80.36.161 (110.80.36.161) 16.068 ms 2.642 ms 2.705 ms 5 61.154.238.129 (61.154.238.129) 5.405 ms 61.154.238.133 (61.154.238.133) 9.038 ms 61.154.238.129 (61.154.238.129) 4.084 ms 6 117.30.27.185 (117.30.27.185) 3.183 ms 117.30.24.213 (117.30.24.213) 5.256 ms 29.543 ms 7 202.97.19.125 (202.97.19.125) 23.899 ms 202.97.23.153 (202.97.23.153) 15.059 ms 202.97.21.69 (202.97.21.69) 12.542 ms 8 113.96.4.130 (113.96.4.130) 20.978 ms 113.96.4.54 (113.96.4.54) 17.600 ms 113.96.4.102 (113.96.4.102) 18.980 ms 9 113.96.4.209 (113.96.4.209) 18.324 ms 25.160 ms 219.135.96.106 (219.135.96.106) 29.135 ms 10 14.29.117.242 (14.29.117.242) 22.918 ms 121.14.67.150 (121.14.67.150) 15.187 ms 14.215.32.126 (14.215.32.126) 15.963 ms 11 * * * 12 * * * 13 * * * 14 * * * 15 * * * 16 * * * 17 * * * 18 * * * 19 * * * 20 * * * 21 * * * 22 * * * 23 * * * 24 * * * 25 * * * 26 * * * 27 * * * 28 * * * 29 * * * 30 * * * ```