It was the visitors, missing six first-teamers through injury and suspension, that started the better though, with Dean Morgan having the first real chance in the ninth minute when he spun and shot well to force Adam Collin into a good low save. Jude Stirling, who had a dire game at right-back then seeing his header from the resultant Andros Townsend corner cleared off the line by Adam Clayton.
With 20 minutes on the clock Morgan had a free-kick deflected away from danger, but against the run of play Carlisle took the lead in the 21st minute. Top scorer Harte notching his 12th goal of the season when, criminally unmarked, he ran in to head home from a Kevan Hurst corner. Hurst then putting in a dangerous low cross seven minutes later which Sol Davis eventually managed to clear in front of Duffy.
Aaron Wilbraham, with a header from a Stirling cross, forced another good save out of Collin moments later, before on 38 minutes he picked up on a poor back header from United skipper Paul Thirlwell, only to fire his volleyed effort straight at Collin. And that would prove costly too as Robson made it 2-0 just sixty seconds later, the left-winger getting on the end of a deflected Clayton shot to drill a well placed finish across Willy Gueret and into the far corner.
And it should have been 3-0 to the home side moments before the interval too when Dobie sent a ball in from the right straight to the weaker right boot of Robson eight yards out. The Carlisle man only able though to spoon his side-footed shot miles over the top as home players and fans alike were left with their hands on their head in disbelief at the miss.
Two minutes after the break and Duffy had a good chance to make the scoreline 3-0, when from a Dobie flick-on, his shot got past Gueret only for on-loan Brighton defender James Tunnicliffe to then able to clear away from the visitors line with a swift punt. Duffy then missing a better opportunity to get his first Carlisle goal bang on the hour-mark, when one-on-one with Gueret, he could only shoot straight at the Dons goalkeeper from the edge of the box.
The on-loan Bristol Rovers striker did get that goal in the 63rd minute though, when after a good Robson run and cross in from the left, he was able to get across to the near-post and side-foot the ball into the net from close range. The home side then making it 4-0 eight minutes later when Robson's ball in from the left was controlled well and then volleyed home by Dobie in the middle of the Dons box.
The visitors had collapsed, particularly in defence by this stage, and within two minutes of coming on as a substitute Joe Anyinsah made the score 5-0. Peter Murphy, in for the injured Evan Horwood, putting in a low cross from the left which Duffy dummied for Anyinsah to run onto and slam a side-footed effort powerfully past a shell-shocked Gueret.
Harte was looking for another goal from a set-piece shortly afterwards but he could only head over the top from a Hurst corner in. With six minutes left on the clock the Dons made a rare second-half break forward but Townsend saw his long-range effort deflect and loop wide off the leg of Danny Livesey. The impressive Luke Chadwick then cutting in from the left before curling a shot across goal as the visitors looked for a late consolation strike.
Carlisle were still looking for their sixth goal of the game though and in the 88th minute Ben Marshall hit in a shot that Gueret did well to push past his far-post. Anyinsah then picking up on a Clayton pass through only to see his powerful drive from the edge of the box crash back off the face of the Dons crossbar. Richard Keogh then protecting the home side's clean sheet in injury time with the last action of the game when he made an excellent diving block on a Lewis Gobern shot.