Specifically the tracking is done here by randomly choosing IP addresses from a pool and correlating connection attempts to the resolved IP to the original DNS

Specifically the tracking is done here by randomly choosing IP addresses from a pool and correlating connection attempts to the resolved IP to the original DNS request. To quote the article: "With 2 IP addresses available in the pool, a 32-bit identifier requires 32 correlated connections. With 256 IP addresses, a 32-bit identifier requires only 4 correlated connections." IPv6 brings it down to just one.