Multiple reports from users since yesterday afternoon have complained of systems incapable of contacting the Internet after having implemented patch KB951748. This patch makes a major change to the way the operating system handles DNS requests. Specifically, it implements a system that enables source port randomization -- a way to scramble the address from which a request is placed -- as a security measure to thwart malicious users from being able to craft false DNS responses, and thus "poison" the caches of DNS servers.
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