An bhfuil a fhios agat? -- Do you know?

This is a general enquiry. If you wanted to ask did someone know a person use aithne and if you were enquiring about knowledge of a subject use eolas.

An bhfuil aithne agat ar Bhrian de Paor? -- Do you know Brian Power?

Níl! ach tá súil-aithne agam air. - - No! (I do not know him.) but I know him to see.

An bhfuil eolas agat ar an nGaeilge? -- Do you know Irish?

Tá. Tá Gaeilge agam. -- Yes. I know (I have) Irish.

An bhfuil an t-amhrán ar eolas agat? -- Do you know the song?