IANAL but there was a patent describing a USB-powered vibrator.
While the idea of a vibrator is not new, and the idea of powering devices via USB isn't new either, the combination of these two non-new ideas was new.
The patent was granted, and when someone (not the patent holder) produced a USB-powered vibrator, they were found in a violation of the patent in question.
Similarly, if someone made a patent about "building a DNS system for data", and someone else used that idea to actually build that system, they may be in a violation of the patent. The more claims (or sub-claims) there are, the more specific the innovation was, and now the question is whether the supposed infringement was actually implementing all of the claims of the patent.