Should an Irish pport have "Londonderry" as county of birth?

Londonderry if i am not wrong is located at Northern Ireland, which is now a part of UK. Therefore, the Irish pport issuer can reject the application for those who are born in the place where is not a place in the Rep of Ireland, even thou Northern Ireland was once a part of Ireland. Irish pport can have the birth place as Londonderry, why not if the person is born in Londonderry and now a full fledged Irish citizen. It doesn't make sense if it cant if the person is now an Irish citizen, likewise if the person is born in Dublin but now a full fledge British citizen of UK. Is what the applicants citizenship counts, not the birth place, since immigration is everywhere not just in Europe.