A Network Analyzer would be needed to make an accurate measurement. Also, to be clear, the measurement is from the center conductor to the outer shield and both connections would be made at one end. Generally a DVM's measurement of capacitance is done at one relatively low freq - 10 to 100kHz. Try it on various lengths of the same cable, plot it per foot, and see what you get. Perhaps start with a 10' cable, measure the capacitance, chop a foot off, and repeat down to 1 foot. Plot the results and show us what you get.