Robert Mahon’s early opener was followed by an own goal and two goals from Evan Ferguson as Ireland raced to a 4-0 half-time lead.
Goals in the second half from Colin Conroy and substitute Calum Kavanagh completed the scoring as Colin O’Brien side dominated proceedings.
It now means that a win over Montenegro on Friday will see Ireland advance to the Elite Round of qualification.
Ireland made the perfect start on three minutes when they took the lead. Armstrong found space on the right and played a dangerous ball across the face of goal. With Irish players lining up to convert it, it was Mahon who finished from close range.
On seven minutes it could have been two. Ben McCormack with a well disguised pass freed Armstrong in the Andorra area but the Shamrock Rovers forward was thwarted by Marc De Castro Prat in the Andorra goal
Ireland were the dominant of the sides, comfortable in possession and dangerous on the counter attack. Mahon in particular was the man causing the visitors the most issues.
Midway through the first half came the game changing moment. Andorra’s Marc Rossell Fort broke through the Irish backline and fired an effort that forced Daniel Rose into a smart save down to his left. From that chance Ireland counter-attacked. Armstrong’s cross looked destined for the boot of Mahon but it came off an Andorran defender for 2-0.
And two minutes later it was three. McCormack’s corner was delivered right under the crossbar and Ferguson rose highest to head in from close range.
Andorra’s heads didn’t drop and Iker Alvarez Sanchez had a long-range effort that flashed just over the crossbar.
But Ireland weren’t letting up and scored a superb fourth. McCormack collected a ball from Tayo Adaramola and he fed in Armstrong who unselfishly put it on a plate for Ferguson’s second of the game.
McCormack continued his influence on the match and almost got a goal his first-half display deserved. His 20-yard effort almost found the bottom corner but De Castro Prat was able to get across to tip it around the post for a corner.
Mahon could have had his second of the game just before half time when he was allowed to drift in from the left between two defenders to fire a shot on goal. Again, the Andorran stopper kept the score line down.
It was Mahon who could have made it five shortly after half time. A through ball found its way to the Bohemians forward in front of goal but he couldn’t make a proper connection to convert.
Ireland eventually got their fifth on 72 minutes when De Castro Prat dropped Conroy’s seemingly harmless cross into the back of the net.
Conroy then turned provider on 79 minutes when he directed his header across goal for substitute Calum Kavanagh to tap home for number six and cap off a perfect night for O'Brien's team.
Ireland: Rose; O’Brien (C) (Barlow 63), Adaramola, Garcia McNulty, L. Kavanagh; Conroy, McCormack (Moran 63), Conway (Crowe 46); Mahon, Ferguson (C. Kavanagh 73), Armstrong (O’Neill 46).
Andorra: De Castro Prat; Rodrigues Trave (C), Alavarez Sanchez (Palou Roca 86), Del Pozo Sanjuam, Tauste; Rossell Fort (Arrahaoui Ferreira 86), Silva Torra (Cerqueira Carvalho 63), Babot Muller, Puigsegur Calvo (Checa Rubio 63); Remolins Planes, Alonso Izquierdo (Sola Garcia 72).
Referee: Aleksei Matiunin (Russia)
Friday, November 15: Ireland v Montenegro, Turner's Cross, Cork, KO 7.30pm
Monday, November 18: Ireland v Israel, Turner's Cross, Cork, KO 2pm