The disruption - which affected everything from global media companies to governments and authorities - has shed light on the vulnerability of a few companies managing the infrastructure on the Internet.
Fastly has apologized and admitted that they should have foreseen the problem.
The bug is linked to a software update from mid-May and Fastly promises to investigate how it came about that it was not discovered until a company's customers changed their settings.
The Fastly CDN service helps large sites, among other things, to keep up the pace by sending data traffic via faster internet routes.