When you visit a website, the data travels across multiple devices and networks to get from the server to your computer or device. These means there are many potential points of failure. Traceroute is a utility that provides a map of the path data packets take to get from the source to the destination.
Traceroute can provide helpful insight in cases where you are unable to connect to your server or website or when experiencing latency, as it will show where in the connection path a failure or slowdown has occurred.
Here we cover how to read traceroute results.
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Reading the Traceroute
- Review the example traceroute (from Linux):
user@machine:~$ traceroute webhostinghub.com
traceroute to webhostinghub.com (216.193.251.47), 30 hops max, 60 byte packets
1 192.168.12.1 (192.168.12.1) 0.559 ms 1.097 ms 1.342 ms
2 10.10.32.1 (10.10.32.1) 14.040 ms 13.977 ms 13.918 ms
3 68.10.14.69 (68.10.14.69) 13.822 ms 13.728 ms 19.129 ms
4 172.22.50.57 (172.22.50.57) 19.069 ms 18.993 ms 20.428 ms
5 172.22.48.33 (172.22.48.33) 20.497 ms 172.22.48.1 (172.22.48.1) 20.359 ms 20.278 ms
6 nrfksysr02-atm151200.hr.hr.cox.net (68.10.8.149) 16.822 ms 11.306 ms 12.288 ms
7 ashbbprj02-ae4.0.rd.as.cox.net (68.1.1.232) 15.190 ms 16.539 ms 16.604 ms
8 10gigabitethernet1-1.core1.dal1.he.net (72.52.92.61) 46.239 ms 46.705 ms 48.099 ms
9 10gigabitethernet1-2.core1.phx1.he.net (72.52.92.253) 52.354 ms 49.544 ms 51.547 ms
10 10gigabitethernet2-2.core1.lax1.he.net (72.52.92.249) 56.785 ms 58.563 ms 57.853 ms
11 corporate-colocation-inc.gigabitethernet3-16.core1.lax1.he.net (72.52.77.38) 51.698 ms 51.134 ms 53.186 ms
12 66.117.11.57 (66.117.11.57) 60.879 ms 61.543 ms 63.765 ms
13 vpimh1.inmotionhosting.com (74.124.202.133) 61.432 ms 59.734 ms 59.963 ms
14 webhostinghub.com (216.193.251.47) 58.863 ms 57.654 ms 59.345 ms - Review the following legend to understand the different parts of the example
- The hop(s) within our network is hop 1
- The hops that route through our ISP (in this case, Cox) are hops 2-7
- The hops through neither our ISP or our network are hops 8-10
- The hops through our network to the destination are hops 11-14
Understanding the Information
The first line of output is information about what we are doing. It shows:
- The target system and that system's IP address
- The maximum number of hops that will be allowed
- The size of the packets being sent (in this case, 60-byte packets)
Then we have one line for each router (or "hop") in the path between us and the target system.
Each line shows:
- The number of the hop
- The name of the system (as determined from DNS) and the system's IP address
- Three round trip times in milliseconds
Latency and Round Trip Times (RTT)
A round trip time (or RTT) tells us how long it took a packet to get from me to that system and back again, this time is called the latency between the two systems.
By default, three packets are sent to each system along the route, so we get three RTTs. For example, on hop six the three packets made RTTs of 16.822 ms, 11.306 ms, 12.288 ms.
Note that the name for the router or system along the route will usually have a three-letter identifier associated with an airport nearby (i.e. iad = Washington Dulles, ord = Chicago, lax = Los Angeles). If it does not or just displays the IP address (which simply means there is no rDNS to provide a hostname) you can attempt to use IP Geolocation to find the location if needed.
For traces across the United States, the average total (not individual) is about 70ms. With this information, we can conclude that the above traceroute is a normal traceroute. For connections from outside the United States (and vice versa) the time may be higher as there is more ground to cover.
NOTE: The speed of a connection is only as fast as the slowest hop, so if all connections are < 20ms and one is 500ms, it will be noticeable as the connection is getting held up.
The Number of Hops
The number of hops a request takes is important to note. If a connection routing from Virginia to California takes 8 hops, that's good, however, if it takes 30, there is a problem with the routing. The amount of hops a request should take will be dependent on the geographic distance from the destination.