Tuesday marked the fourth anniversary of "Safer Internet Day," a 40-country effort to raise awareness about computer and Internet security. But the day probably didn't feel too safe for the dozens of unheralded technologists responsible for defending the World Wide Web against one of the most concerted attacks against the Internet's core since a similar assault in 2002. Details about the sources, size and methods used in the attack are still trickling in, but like the celebration of Safer Internet Day, it's not clear that anyone using the Web at the time even took notice. That's largely a good thing,...