The Government is to consider community by community which areas should be offered state-sponsored high-speed broadband.
A national mapping exercise to identify parts of the country which would not be adequately served without official intervention was launched on Monday by Communications Minister Pat Rabbitte.
"We will work our way through a map of Ireland, community by community," he said.
"We need to see which streets and roads, which towns and villages will be offered fast broadband by commercial operators.
"That's the only way to spot the gaps that we will need to fill with state supported investment."
He said the nationwide mapping project was a key step in delivering the National Broadband Plan, which commits to achieving speeds of a minimum of 30Mbps or higher to all parts of Ireland, through a combination of public and private investment.
The exercise will help identify where advanced broadband services are already in place or planned within three years. The Department of Communications, Energy and Natural Resources is seeking information relating to the infrastructure used by telecoms companies to provide those services and the extent of the coverage.