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Doing a ping, traceroute or telnet
PING lets you know if a machine is accessible through the Internet. You can also use this tool to check if you are contacting the right machine, e.g., after a DNS change, by looking at the IP address obtained. It is possible to ping a domain name, a hostname, or an IP address.
TRACEROUTE (TRACERT) is used to examine the route taken by your connection to reach the target machine. This makes it possible to determine the origin, for example, of a web page display issue or slow connection problems.
TELNET is used to test the connection to a server without taking into account the additional settings of a mail client or an FTP client in order to determine the origin of a problem. If the connection does not pass through an SMTP server, for example, you will have to look to see if your firewall is blocking port 587.
Actions to be carried out
Under Mac OS X search for Network Utilities (Fig. 1)
Go to the Ping, Lookup or Traceroute tab depending on what you wish to test.
You may also use the Terminal and follow the instructions given below.
Under Windows, open Execute and type cmd
In the window that appears, type one of the following, depending on what you wish to test:
Replace [server] with the server name or IP address
telnet [server] [port]
The same goes for [port]
For Android, use the free Simple Telnet Client app that lets you test very simply using 2 fields to be filled in (server: mail.infomaniak.com and port 143.
Find out more
Some machines block pings; this does not mean that such machines are not reachable via the web.
Some routers send out "*" instead of information; this means they don't accept traceroutes and does not mean that the connection is lost.
The Telnet command is often disabled under Windows and you will have to enable Telnet services under Windows Features.