Ulster notched up their third consecutive bonus point RaboDirect PRO12 victory to keep their play-off hopes alive with Stefan Terblanche's last-minute try bringing Brian McLaughlin's side maximum points from a 30-12 win.
The South African's score came after Ulster had been reduced to 14 men for the second time in a game which the Dragons had enjoyed plenty of possession and territory but had been unable to get across the home side's line.
First half tries from Robbie Diack and Ruan Pienaar set Ulster on their way before Craig Gilroy added another. Pienaar kicked two conversions and two penalties to end a wet and cold night with 15 points.
Jason Tovey bagged all the Dragons' points with the boot.