I don't get how that could be called passive. This is making your browser issue requests or am I missing something?
That being said, I highly doubt there are many requests being made to Bangalore, India and this appears to require requests to a wide array of locations all over the world.
Additionally I once made a map of destinations from our school's "security lab" network. This is 30 minutes of traffic: https://snag.gy/aJqrg2.jpg
The map is a modified version of the one generated by Wireshark (circles are proportional to the amount of data going from/to that IP address). It seems to use Maxmind's GeoIP database.
You visit a website that uses one or more CDNs for its big resources, and uses Cedexis to choose CDN node. When you first visit, Cedexis instructs your browser to retrieve small resources from some/all CDN nodes. Based on timings and throughput, it then chooses a CDN node to use for big resources.
If Cedexis does its job well and obtains the right data for Cedexis' purposes, then the passive observer also gets optimally usable data.
Another comment mentioned someone monitoring your traffic and noting your RTT (roundtrip time) for various IP addresses around the world. That seems much more likely.