Even that isn’t sufficient, as it’s very easy to get ahold of /48 blocks. To do a good job of this, you need to actually break things down by ASN and look at th

Even that isn’t sufficient, as it’s very easy to get ahold of /48 blocks. To do a good job of this, you need to actually break things down by ASN and look at their policies for handing out IP addresses to figure out what granularity to use.