Spammers can't use dotted quads or any other literal IP address, since SpamAssassin won't let it through, since it looks too much like spam. So, spammers need cheap and plentiful -- dare we say 'too cheap to meter'? -- domain names. The DNS industry is only too happy to provide these domain names, cheaply and at massive scale. The end result is that 90% of all domain names are crap, with more on the way. DNS registrars and registries sometimes cooperate with law enforcement and commercial takedown efforts since it results in domains that die sooner thus creating demand for more domains sooner. Spammers and other abusers of the Internet commons sometimes try to keep their domains alive a little longer by changing name server addresses, or changing name server names, many times per day. All of this action and counteraction leaves tracks, and around those tracks, security minded network and server operators can build interesting defenses including DNS RPZ, a firewall that works on DNS names, DNS responses, and DNS metadata; and NOD, a feed of Newly Observed Domains that can be used for brand enforcement, as well as an RPZ that can direct a DNS firewall to treat infant domain names unfairly. Dr. Paul Vixie, long time maintainer of BIND and now CEO of Farsight Security, will explain and demonstrate."