  Monitoring performance and availability are critical to operating successful
content provider networks. Internet measurements provide data needed for
traffic engineering, alerting, and network diagnostics. While there are
significant benefits to combining server-side passive measurements with
end-user active measurements, these capabilities are limited to a small number
of content providers with both network and application control. In this work,
we present a solution to a long-standing problem for a method to issue active
measurements from clients without application control. Our approach uses
features of the W3C Network Error Logging specification that allow a CDN to
induce a browser connection to an HTTPS server of the CDN's choosing.
