Favourable results such as rise in profession, good health and general prosperity would occur during the Dasa period of the lord of the Lagna if he is powerful.

• Transiting planets 
• Placement in Bhava-sandhis
• Relation between the two Dasa planets

A thorough grasp of basic principles relating to Dasa periods and Sub-Dasa periods is a sine quo non for making an accurate reading of a Natal Chart of an individual.  It is the Maha Dasa and Sub-Dasas in operation at a given time that provide the key to determining as to when certain planetary positions and combinations as well as specific Arishta yogas and Subha yogas would produce their effects.  Timing of important events in one’s life like marriage, child birth, disease and death is based on the interpretations of effects produced during specific Dasa periods. Hence the great significance of a sound knowledge of basic principles relating to Dasas and Sub-Dasas in predictive astrology.  We propose to present several Dasa principles culled from classical works on Vedic Astrology for the benefit of our readership. 
Favourable and unfavourable results 
If there is a relation between the 10th House And the lord of the 11th  House, a Rajayoga which means an event signifying great success and high achievement  would occur during the Dasa period of the lord of the 
11th House. 
If the lords of the 9th and 10th House are placed in the 9th or the 10th, a Rajayoga would occur during their Dasa periods.
The Antar Dasa period of the 9th lord in the Maha Dasa period of 5th lord is very favourable.
The Dasa period of the 9th lord combined that of the 5th lord bestows status, profession, and children. The period of the 4th lord associated with that of the 10th lord gives similar results.
Favourable results such as rise in profession, good health and general prosperity would occur during the Dasa period of the lord of the Lagna if he is powerful. 
The Dasa period of the 10th lord placed in the 9th would give honours, wealth and happiness.  The Dasa period of the 10th lord associated with the 4th would produce happiness. 
If the lord of the 4th and 10th Houses have exchanged Houses, their Dasa periods would produce favourable results. 
The Dasa period of the 5th lord placed in the 4th would bestow much good.  The 4th lord placed in the 10th House would bestow career success and happiness. 
The Dasa period of the planet associated with 5th and 10th Houses too would bestow a good profession.
Planets in Bhava-sandhis, junctional points, would not produce full results during their Dasa periods. The Dasa period of Saturn, if it happens to be the fourth Dasa, would be unfavourable. 
Jupiter’s Dasa would be unfavourable if it happens to be the 6th Dasa.
The Dasa periods of the lords of the 6th and the 8th would produce much harm unless they have acquired beneficence otherwise. 
A planet produces in his Dasa such results as indicated by his lordship, association, location, and aspect.  For example, the 2nd lord placed in a favourable position, would give wealth during his Dasa. 
The Dasa results are modified by the effect of transiting planets. 
The 3rd lord gives new friends, help from brothers, leadership and physical during his Dasa.
The general effects of the Maha Dasa get modified by the planet that rules the particular Bhukti or the sub-period. In such cases, the effects both planets produce are to be determined taking into consideration the relation between the two planets.  For example, if the two planets are friends, good effects would get heightened. 
Unfavourable results are to be predicted, if the major Dasa lord and the minor Dasa lord are placed in the 8th, 12th, or the 2nd positions from each other.