Hi Marco, let me plug a project of mine: https://ihr.iijlab.net/ihr/en-us/metis/selection you can enter the number of probes (aka unique ASes) you want to use in the form and then click on "Go". At the bottom of the page you will then find a JSON snippet which replaces the "probes" field of the API spec provided by the Atlas webinterface. This selection tries to prioritize ASes that are "far apart" from each other according to the distance metric in the form, so the order is not randomized, but depending on what you want to achieve might be random enough. If you want to do multiple iterations with a randomized AS set each time, I guess you will have to build this yourselfes. However, you could enter 4000 for the number of probes and the API spec will contain fields for all ASes with connected Atlas probes, which you could use as a starting point. Also note that you might not get the exact number of probes requested, since some ASes only have one probe and if it's overloaded it won't participate. Best, Malte