imgix outputs a default /robots.txt file for every domain with the following:
User-agent: * Disallow:
The "User-agent: *" means that the instructions will apply to all search engine robots, such as Google's Googlebot. The "Disallow: " tells each robot that it has complete access to crawl every URL associated with the domain. This is equivalent to having an empty /robots.txt or none at all. For more information on /robots.txt, please refer here: http://www.robotstxt.org/robotstxt.html
Requests made by robots are counted as regular requests, which means they contribute toward the master image and bandwidth calculations for billing.
Please contact support@imgix.com if you would like to alter the /robots.txt file associated with any of your domains.