For a common mid-west surname like Burke you would probably need a few more details when searching a large county like Tipperary to narrow down the results - ideally the name of the parish, and also if possible some family details - e.g. father's name, names of some siblings etc.
RootsIreland dont have all the available Tipperary records, and records for most of one Diocese are not included.
If you know the town or area you can narrow down the search by denomination and parish on RootsIreland, but you need to select the relevant county centre first. The 'all-Ireland' search doesn't allow filtering results by parish. Note Tipperary records are often divided in to North and South Riding, as is the case for the records on RootsIreland. The town of Roscrea is in Tipperary North.
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