By combining its existing 1m names (gathered from people who had responded to previous offers on tinned goods) with lists of similar households bought from brokers, Heinz has built up a database of 4.6m people to send a copy of At Home, a free magazine of recipes which also promotes its products.
When one of the registrars sends an addition, deletion or modification to a DNS record, SnapNames receives a copy of that change and maintains its own comprehensive database of domain name registrations called Whois.