Dún Laoghaire–Rathdown is a county in Ireland. It is part of the Dublin Region in the province of Leinster. It is named after the former borough of Dún Laoghaire and the barony of Rathdown. Dún Laoghaire-Rathdown County Council is the local authority for the county. The population of the county is 206,261 according to the 2011 census.