I research the Irish Family History Foundation's database. It contains 12,000,000 surviving rcds for abt 65% of Irish counties. Rcds are increasingly sparse B4 1840, rare B4 1800.
Note 1 - Without a KNOWN parish, the chance of an ancestor's rcds NOT being in this database is AT LEAST 35%.
Note 2 - Only 1/2 of Co. Cork's rcds are in this database.
Note 3 - The RC church kept control over most parish rcds from Tipperary (north). These are ONLY available thru the Tipperary Family History Research center at a substantial fee (regardless of outcome).
For Cath(erine) Kiely B 1840 +/- 2 yrs somewhere in Ireland with a father's forename unknown, I found 20 rcds: 1838 LIM, 1839 GAL, 1839 CRK, 3-1840 TIP, 1840 LIM, 2-1841 CRK, 1841 TIP, 2-1841 LIM, 4-1842 LIM, 1842 TIP, AND 3-1842 CRK. You will need an exact DOB, placename, and/or parent name to select the right rcd. The mother's name is your key to this problem. A view of the right rcd should show which, if any, of these rcds has this name.
Google the Foundation's name to lead you to this database. Register, opt to be notified as rcds are added and browse. Pls post your search results to my genforum msg.