I would briefly go into the theoretical aspects of Vedic astrology to answer this question. Vedic astrology can (theoretically) assess a chart by the methods mentioned below.

1. The Varga system which is based on the planetary degrees at the time of birth. Charts can be drawn and studied and analyzed based on it. Most of the information can be gained by an expert astrologer from the lagna chart itself but there is always an option to dig deeper.

2. The Dasha system which is based on the Moons position at birth. These Dashas or the ruling period of various planets keeps changing during one’s life and produce different results. It includes Mahadasha and the Anatardasha periods.

3. The Gochara, or planets transiting trough various houses of the chart and their result. The planet transits a sign for different time periods producing different results.

4. The Prasna Kundali system, is an independent method, where the chart is drawn based on the time of the query. It is not related to the above three methods which give predictions based on time of birth of a person. The analysis or the results by both the ways should be the same

If you are confused, I would say this – birth chart analysis in the hands of an expert and experienced astrologer is a seamless process and once he see a birth chart with placement of planets in different houses, the angular position of the planets in degrees, the dasha table and transit of plants through various house(s) then he is able to quickly answer the question that is asked about any specific time period either in the past, present or future. This is answering a question based on the analysis of a birth chart and is different from Prasna Kundali.

Prasna kundali in my experience has been found to be lacking in giving accurate answers and more often than not astrologers also refer to the birth chart method for confirmation whereas doing predictions by the birth chart method does not required a confirmation by the prasna kundali method.

In both the cases a strong intuitive power is needed after the chart is drawn either based on the time of birth of the individual or the time of asking the question.