Traceroute
Traceroute is a commonly used tool for troubleshooting network and internet traffic problems. A traceroute shows you the route over the network between two systems, listing all the intermediate routers a connection must pass through to get to its destination. By analyzing the steps, users can pinpoint why a connections to a given server might be poor. Additionally, a Traceroute gives insight into how your ISP connects to the Internet as well as how the destination server is connected as well.
Traceroute works by sending a series of packets to the detination host. These Internet Control Message Protocol (ICMP) packets can be traced through the time-to-live (TTL) Internet Protocol parameter which are monitored by the recieving router. The receiving routers decrement this parameter and discard a packet when the TTL value has reached zero, returning an ICMP error message (ICMP Time Exceeded) to the sender.
Traceroute works by increasing the TTL value of each successive batch of packets sent. The first three packets sent have a time-to-live (TTL) value of one, expecting that they are not forwarded by the first router. The next three packets have a TTL value of 2, so that the second router will send the error reply. This continues until the destination host receives the packets and returns an ICMP Echo Reply message.
The traceroute utility uses the returning ICMP messages to produce a list of hosts that the packets have traversed through on their way to their destination. The three timestamp values returned for each host along the path are the delay (aka latency) values, typically measured in milliseconds for each packet in the batch.
Traceroute may not list the real hosts that it encounters. It indicates that the first host is at one hop, the second host at two hops, etc. The Internet Protocol does not guarantee that all the packets take the same route. Also note that if the host at the first hop does not reply, the hop will be skipped in the output.
How to perform a traceroute to your website or server
The traceroute program is available on most computers which support networking, including most Unix systems, Mac OS X, and Windows 95 and later.
On a Unix system, including Mac OS X, run a traceroute at the command line like this:
traceroute server.name
If the traceroute command is not found, it may be present but not in your shell's search path. On some systems, traceroute can be found in /usr/sbin, which is often not in the default user path. In this case, run it with the full path:
/usr/sbin/traceroute server.name
On Mac OS X, if you would rather not open a terminal and use the command line, a GUI front-end for traceroute (and several other utilities) called Network Utility can be found in the Utilities folder within the Applications folder. Run it, click the “Traceroute” tab, and enter an address to run a trace to.
MTR is an alternate implementation of traceroute for Unix. It combines a trace with continuing pings of each hop to provide a more complete report all at once. It is available here.
If you are stuck with Windows, the command is called tracert. Open a DOS window and enter the command:
tracert server.name
Free Uptrends traceroute tool
You can use the free Uptrends traceroute tool to perform a traceroute. If you are experiencing uptime issues with your site, you may wish to register for a free Uptrends account which will alert you whenever your website or servers experience downtime. In the event your website or server has a failure, Uptrends will perform an automatic traceroute and send it to you by e-mail alert. You will be able to view the automatic traceroute in the probe log report so you can pinpoint issues that caused downtime during previous attempts to visit your website or server.