Ex Dividend and Selling of Shares

Let’s assume that the 21st of March is designated as the ex dividend date for stock ABC.

So from my understanding if a companies ex dividend date is March 21st and you buy the shares to that company before market close on March 20th you will qualify to receive the dividends.

What if you were to buy in aftermarket trading on the 20th but before premarket on the 21st. Would those shares qualify?

Also if you were to sell those same shares (that were purchased on the 20th prior to the ex dividend date) at market open on the 21st would you still qualify to receive those dividends?