1) Agreements with ISPs [most accurate]
2) IP Spidering via traceroutes / RIPE/etc data.
3) Agreements with third parties that have IP/Address mapping due to data supplied from users. [least accurate]
That'd be my guess anyway.
2) IP Spidering via traceroutes / RIPE/etc data.
3) Agreements with third parties that have IP/Address mapping due to data supplied from users. [least accurate]
That'd be my guess anyway.