Connacht Schools dominated this tie at Castle Avenue on Saturday, with their bigger pack punching holes in the defence of Leinster Schools A.
Conditions were tricky, to say the least, but Connacht adapted better and Brian Kelly knocked over a penalty from a slight angle after five minutes.
The Connacht pack then drove forward before Ambrose Conboy made the final push for a score on the right-hand side.
Kelly converted to bring Connaught in to double figures and a further score from flanker Alan Carney underlined the difference between the sets of forwards.
Jeff Moore put Leinster on the scoresheet with a penalty but Connaught replied soon afterwards with an attack up the middle that yielded their third try, from centre David White.
Kelly converted to put his side
22-3 ahead at the interval.
Although Ronan Connolly offered Leinster some respite, Niall O'Brien ended the game fittingly by intercepting in the Connacht half and racing clear for a memorable score.
LEINSTER A: C Glynn (St Mels), P Mc Kinley (St Columbas), B Keegan (Presentation Glas thule), D Handcock (Mount Temple), P Taggart (St Columbas), J Moore (Mount Temple), B O'Connor (St Conleths), K Law (Newpark), G Mercer (Mount Temple), K Ellis (Mount Temple), L Jenkinson (Newpark), E Moore (Sandford Park), P Forde (Sandford Park), R Connolly (HFDLS Skerries), N O'Car roll (Mount Temple). Replacements: G Ryan (Newpark) for Moore.
CONNACHT: O Grennan (Sligo GS), N O'Brien (Presentation Athenry), M Mc Donnell (Garbally), D White (St Muredachs, Ballina), F Fullard (Colaiste Iognaid), B Kelly (Garbally), M O'Dea (St Joseph's, Galway), C Glennean (Garbally) C Cunningham (Colaiste Iognaid), A Conboy (St Joseph's, Galway), C Murphy (Gort CS), A Maher (St Joseph's, Galway), A Carney (Colaiste Iognaid), I Kelly (Garbally), E Brandon (St Mary's, Galway). Replacement: P O'Farrell (Colaiste Iognaid) for Grennan.
Referee: T McCarney (URS)
Welsh rebel club Swansea scored 16 tries in crushing Amman United 7-100 in the second round of the Swalec Cup.
Swansea were forced to enter the competition by the Welsh Rugby Union after deciding not to play in the Welsh Premier Division.
The All Whites kicked 10 conversions and wing Simon Davies scored three tries.
Fly-half Lee Davies scored 22 points, with two tries and six conversions.