I was told that in order to produce primers, the DNA sequences at the 3' end of the template strand must be known, and that these primers are complementary to 3' ends of the template DNA. However, that causes me confusion when I view the following image from my college class, which show that the primers anneal to the template DNA further down the strand:

I was told that in order to produce primers, the DNA sequences at the 3' end of the template strand must be known, and that these primers are complementary to 3' ends of the template DNA. However, that causes me confusion when I view the following image from my college class, which show that the primers anneal to the template DNA further down the strand:

So do the primers need to be complementary to the last 20-35 bases at the 3' ends of the template DNA or simply to any portion of 20-35 bases near the 3' end?