The way it was performed is fairly straightforward:
1. Use a stateless scanner to send a Ping request to every public IPv4 address
2. Keep track of which IPs responded with a Pong
3. Find out where the IP is physically located using a GeoIP library (i.e. translates from x.x.x.x -> latitude/ longitude)
4. Draw the map
Steps 1-3 took about 5 hours and the final step took 12 hours. This is possible because nowadays we have the technology (stateless scanning) to very efficiently talk to millions of devices on the Internet at once.
Read more:
http://www.businessinsider.com/this...onnected-to-the-internet-2014-9#ixzz3DK9asSb2