The following was written by the Irish Family History Foundation:
The Advanced Search facility is now available on All Ireland Searches on the main search page of www.rootsireland.ie.
Please note that counties Limerick and Sligo do not participate in the Advanced Search facility and will be excluded from the results of an Advanced Search on the All Ireland site.
The Advanced Search facility is also available for each county centres' data with the exception of Co. Limerick and Co. Sligo.
Note that Standard search will continue to work across all counties.