Netalyzr - internet connection test

For many users, the Internet connection is characterized by only one parameter - the connection speed. In reality, the quality of the connection is influenced by a huge number of factors, as a result of which even specialists can find it very difficult to identify the causes of connection problems.

Researchers at the International Computer Science Institute (ICSI, Berkeley, USA) have developed Netalyzr , a user connection testing service. The service is implemented as a Java applet, so for successful launch, Java support must be enabled in the browser.
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When launched, Netalyzr performs a large number of different tests using the development server. In total, the applet contains 38 tests, some of which have subtests. Here are some examples of basic tests: port blocking, the presence of hidden HTTP proxies and caches, DNS query manipulation, the presence and behavior of NAT, problems with MTU and fragmentation, IPv6 support, modem buffer size, etc. After testing is completed, the user is presented with a results page ( example ), on which the individual tests are divided into categories and marked with different colors depending on the outcome. A good review of non-expert tests was published by New Scientist.

ICSI researchers also save the results of all sessions on their servers for further analysis. About two months ago, an article appeared at one of the conferences detailing the service itself and the results of data analysis. At the time of publication, the applet was launched 130K times with 99K different IP addresses. The geography of launch sites looks like this:



Data analysis revealed several prevalent problems: excessively large uplink buffers, leading to an unjustified increase in network latency; bad DNS resolver performance; difficulties with packet fragmentation; substitution of DNS query results by some providers and OpenDNS; etc.