1. A method comprising: generating a plurality of different update name lists comprising: registering domain names of sites from which malicious code protection update information can be obtained; and selecting subsets of said registered domain names to create said different update names lists, each of said different update name lists comprising a subset of said registered domain names that is different than subsets of said registered domain names of the other of said different update name lists; and providing said malicious code protection update information including said different update name lists to host computer systems, wherein different ones of said host computer systems receive different ones of said different update names lists, said malicious code protection update information for use by security applications of said host computer systems to detect malicious code on said host computer systems.