Assume that in range A2:A11, cells have been validated to allow a person to enter Y or N. In B2:B11, cells should be validated based on the entry selected by the end-user in range A2:A11. So, if a user selected Y in cell A2, then a drop down should appear in cell B2, allowing him to choose from Delhi, Mumbai, Chennai and Kolkata. If the user selects N in cell A2, he should be able to enter any value in cell B2.
To accomplish this, try the following procedure
1. Type Delhi, Mumbai, Chennai and Kolkata in I2:I5 and assign it a name (Ctrl+F3), say source1
2. In A2, select Y
3. In cell B2, go to Data > Validation > Allow > List > Source > =IF(A2=”Y”,source1,B2)
With Y in cell A2, B2 will show four cities in the validation drop down. When the value in cell A2 changes to N, the user will be able to enter any value in cell B2.