Trailrunner7 sends in this excerpt from Threatpost: "As major botnet operators have moved from top-down C&C infrastructures, like those employed throughout the 1990s and most of the last decade, to more flexible peer-to-peer designs, they also have found it much easier to keep their networks up and running once they're discovered. When an attacker at just one, or at most two, C&C servers was doling out commands to compromised machines, evading detection and keeping the command server online were vitally important. But that's all changed now. With many botnet operators maintaining dozens or sometimes hundreds of C&C servers around the world at any one time, the effect of taking a handful of them offline is negligible, experts say, making takedown operations increasingly complicated and time-consuming. It's security through ubiquity. Security researchers say this change, which has been occurring gradually in the last couple of years, has made life much more difficult for them. ... Researchers in recent months have identified and cleaned hundreds of domains being used by the Gumblar botnet, but that's had little effect on the botnet's overall operation."