Measurement Lab is our top pick for the best overall speed test due to its history, open platform, and mission for open data.Internet speed tests are essential to ensure you’re experiencing speeds as advertised by your internet service provider (ISP).Just as it happened this last Friday here in Italy.Find out if your internet provider is living up to its advertised speeds starts by taking an internet speed test. STORM ALERT: 12 out of 14 sites are unreachable! Or a site such as Down Detector will keep me informed about the "Internet weather".Īctually, on my home server there's a Squid cache and the error page contains the last data retrieved successfully from down-site statistics, so I may see something like is not reachable All I need now is for to be up :-), then checking If everything goes OK at this point I know that the connection is in working order, in general it may still fail for some sites. That will not only tell me whether the problem is the DNS or the ISP, it will often allow me to work around the interruption. In case of DNS failures I may try a traceroute of the DNS IP address (or a different DNS such as OpenDNS's ones). While if the DNS server is unreliable, the same query might return the address of the captive portal for wifi $ host Ĭnet has address 192.168.4.200 In order to avoid DNS caches, I sometimes use some domain which will answer to all queries no matter what. you want to see that, after your gateway, some extra nodes are responding.įor example in Windows XP at home I have: 1 run a traceroute with short TTL (actually, a TCP traceroute such as the one provided by hping is better) of a surely external address, 8.8.8.8 is okay.query local network configuration and retrieve gateway and DNS server.But seeing as how you use a numeric IP instead of a domain name, you've already cottoned up to the fact that you might have IP connectivity and still "no Internet" because of DNS problems.Ī complete diagnostic would have to start close to your PC. "internet is available" is a much more complicated thing than simply "Is 8.8.8.8 (or other IP) reachable".įor a quick, dirty and not always reliable check, pinging 8.8.8.8 is good. Of course, I could use 8.8.8.8 on purpose, reasoning that if I can't reach Google's infrastructure, I don't care about the reason, I might as well try with the backup router. In that case, by comparing the results of traceroute -n in normal and abnormal conditions, I see that the first hop to 8.8.8.8 (or any surely external site) that does not respond is 151.6.68.45, which is part of my ISP's infrastructure.īy using that IP as a "check-alive" host (after repeating the test just to be sure it is fixed), I can detect an ISP anomaly without getting a false positive in case the ADSL is OK, but the ISP routing has troubles. On my system I can emulate this situation by failing the ADSL authentication.
You want to ping the "nearest" fixed IP that is non-routable when the ISP enters traffic overload state.