Have you found the correct location of the test point?

Test points are very important and familiar to testers. The accuracy of the test is closely related to the location of the test points. Incorrect test points will lead to incorrect test results, thus affecting the judgment of signal quality. Do all testers know where the appropriate test points should be and the importance of test points? Not at all. Any job has proficiency and experience, and testers are no exception. For experienced and skilled testers, various precautions and key points in the test process are naturally clear in mind, but for junior testers, they often make many low-level mistakes, such as the magical test points we are about to talk about. The thing is, a friend's DDR3 system is not running properly, so he used an oscilloscope to test the DDR3 clock signal, and the waveform obtained was non-monotonic (Figure 1). What? The clock signal is non-monotonic? That's a very serious problem. No wonder the system is not running properly. This needs to be found by the PCB designer. Is   
this really the case? When I saw the non-monotonic waveform, I first asked my friend where the test point was. My friend said it was at the string resistance in front. Haha, good guy, no need to ask any more questions. Regarding the test point issue, let’s first look at the topology of the clock signal in Figure 2 below.