You create a route, in a router you control, that sends packets to that address into the bit bucket. Ideally its an edge router that everyone in an organization shares, or at an ISP which will protect anyone using that ISP.
Various companies will sell you a list of currently known malware domains (like spammer lists) which you can feed into a router to create blocks for them. Is that what you are asking?
Well, sometimes the black hole route leaks out. A (the???) Pakistani telco was blocking YouTube inside the country, but accidentally advertised itself as the shortest route to YouTube for a good chunk of the world. This was back sometime around 2008-2010.
