DONT is a convention which is used over a 1NT bid by the opponents

X = a one-suited hand
2C = 2-suited hand -- clubs and a higher ranking suit
2D = 2-suited hand -- diamonds and a higher ranking suit
2H = both majors
2S = spades (and could be weak)

If partner doubles -the relay bid for the double is 2C and partner will either pass (with clubs) or bid his suit.
If partner bids 2C or 2D, you would pass with 3clubs/diamonds or relay to the next higher ranking suit asking partner to correct to his second suit.
2H is showing both majors so you would pass with 3H or correct to spades.
2S is showing spades--unless you were strong you would pass the 2S bid by partner.

Hand 1

Partner	96 KQJ54 7 A8742
T876 T6 A86 9653		KJ7 A92 KT32 KQJ
	AQ53 873 QJ954 T

North	East	South	West
Pass	1nt	Pass	Pass
2C	Pass	2D	Pass
2H	Pass	Pass	Pass

East openes a Strong Notrump.

When it comes around to North She bids 2C*. This partnership has agreed to play DONT.

2C* shows a 2-suited hand with Clubs and a higher ranking suit. Since her partner has no support for Clubs he bids 2D* artificially asking his partner to bid his other suit.

North bids 2H and South passes content to play there.

Hand 2

Partner	43 Q98 A62 J7654
Q62 7432 987 Q32		T3 AKJT KQT AT9
	AKJ987 63 J543 K

North	East	South	West
Pass	1nt	DBL	Pass
2C*	Pass	2S	Pass
Pass	Pass	-	-

East openes a Strong Notrump.

South doubles to show a 1-suited hand and some values. This partnership has agreed to play DONT. The 2C bid is a relay and when it comes around to South she bids her Spades. North will pass with a limited with only moderate values. Game is unlikely.

Fifth Chair and Anna Marsh Bridgeguy's Website ACBL Site DONT Quiz