Northern were always going to have to attack in response, and their hopes were realistically dashed within the first over, with two wickets falling to Seth Rance's bowling.
At 125-7, a huge defeat looked on the cards, but Daryl Mitchell gave the contest a much-needed jolt with a breath-taking innings, smashing eight sixes in a career-best 120 from 107 balls.
He got assistance from number 10 batsman Jimmy Baker, who made 48 as the pair combined for a New Zealand record ninth-wicket partnership of 117.
However, when Mitchell fell, so did the Knights' chances of a miracle win, CD wrapping up the comfortable victory to sit in third on the ladder.
They're one point behind Auckland in second, who held on to beat Wellington by 12 runs at Eden Park Outer Oval.
Michael Guptill-Bunce made 73 on debut while Hong Kong international Mark Chapman added a quickfire 62 as the hosts compiled 288-9.
Michael Papps (72) and Tom Blundell (73) kept Wellington in the hunt, but they were always behind the asking rate and were eventually defeated by a slew of late-order runouts.
Auckland sit three points behind Canterbury, who rebounded from a horror start to beat Otago by 47 runs.
The Gary Stead-coach side found themselves at 8-3 after seven overs, but four players reached 40 in the middle order to guide them to a competitive 257-7.
In response, Otago lost consistent wickets to be all out for 210, giving Canterbury a handy buffer at the top of the ladder.
