A method of measuring, for communication paths between a networked computer and at least one other networked computer connected via a network performance, network information to detect network performance degradation and diagnose source(s) of the performance degradation. The diagnosis may be performed by a progressive elimination of possible sources. Network performance degradation may be attributed to problems at a local network or the Internet. The problem sources on the Internet may comprise, for example, an internet server provider (ISP) or a single remote server in communication with the networked computer. A network performance baseline established and maintained for each path may be employed in diagnosing the network performance degradation.