Tracert nome host
Segno qui alcuni appunti in merito:
As you can see above, the resulting text gives you a list of hops between you and the remote host, and three columns of replies.
That’s because the tool sends three ECHO REQUEST packets over to each hop.
A good reply time is below 100 ms. If your result shows a very high latency, then that may be an indication something is wrong with that particular hop.
Any star you see means the packet did not return. If there are 3 stars for a particular IP, then the tool considers that host timed out. This doesn’t necessarily mean that a router is down. What usually happens is that the next host in the path has a firewall, and is blocking your requests.
A much worse type of reply to see is “Destination host unreachable”. When you see that, then it pretty much means that the next router in the list is down, or can’t be reached. This could be for a number of reasons, like the device itself isn’t up anymore, or there’s a routing issue and your packets can’t get there. If that happens, then the problem is most likely at that location.
If the problem is outside of your own network, whether you work in a corporation and have to deal with a corporate network, in a school, or some other type of organization, then it’s much harder to diagnose the issue and correct it. Often, the problem may be with your Internet provider.
If the result you see from traceroute is some big latency, or packets being dropped, and it seems to be happening just as they get out of your network, then perhaps your provider has a congested network.
If the problem seems to be further away than your local ISP, and a call to their support line is unlikely to help much, you can go to the Internet Health Report, which is a site that monitors performance between various backbones in the US, or the Internet Traffic Report for worldwide charts.
Finally, the problem can sometimes be inside of your network. If a user, or multiple users, have problems accessing the web, especially if it’s everything that seems slow, but you know that your outside connection is fine, then something may be wrong somewhere within your building. A lot of things can actually go wrong. An unshielded ethernet cable may be too close to a power cord, causing interference. Perhaps someone plugged in a device incorrectly, causing data loops. Or maybe a computer or device on the network is using up all the bandwidth. The best way to find out exactly what’s happening is by using a network tap. If you manage a network, you should always have a tap available with you.
A network tap almost always works the same way. It’s a hardware device with at least three ports, which you can connect anywhere in your organization, between points A and B, and all it does is copy all the data that goes through it to a monitor port. In many cases, this is preferable than using a software tool, because you get far more information. The problem may not be at the TCP/IP level. It could be happening at the frame level, and only a tap could show you that.
[FONTE http://m.techrepublic.com/blog/networking/is-the-internet-down-troubleshooting-network-issues/6184 ]