Abstract: Described is a technology by which a content server downloads an active content measuring tool object to a client request for a page. When loaded, the measuring tool object makes network measurements, including by direct socket access, and return measurement results. As part of its operations, the measuring tool object may request measurement assignments from a central controller, and/or return those results to the central controller. Measurement assignments may be directed towards determining a round trip time/latency, measuring throughput, packet loss rate, detecting in-fight modification of content and/or detecting the presence of a middle box, including the presence of a caching proxy server middle box. The measurement results may be used to evaluate hypothetical deployment of a number of servers and/or geographic locations for those servers.

Abstract: Charting a content distribution system (CDN) involves identifying a set of DNS servers that may be used as vantage points to test delay performance to a CDNs content server. As provided herein, to identify potential vantage point DNS servers, a set of authoritative name servers is identified and, from that set, those authoritative name servers that respond to a DNS query are identified as responsive authoritative name servers. Identifying a CDN content server that serves a particular vantage point DNS server involves retrieving an IP address for the CDN content server from a DNS query to the DNS server corresponding to the vantage point. The delay performance between the vantage point DNS server and the CDN content server can then be determined. Further, one can determine locations to deploy new data centers for a CDN based on delay performance, A delay from one or more vantage points to an existing CDN's DNS servers can be measured, and desired rank of locations can be generated.