誰だか知ってる

know who someone is

→ 誰
phrase Uncommon #16,884
know who someone is Casual form; 知ってる is a contraction of 知っている.
JA: あの人が誰だか知ってる?
EN: Do you know who that person is?

花婿誰だか知ってるか?

Do you know who the groom is?

— きっと、うまくいく (2009)

誰だか知ってるわ

I know who that is.

— マルコムX (1992)

自分が誰だか知ってるのか?

Do you know who I am?

— GHOST IN THE SHELL (1995)

トムの彼女って、誰だか知ってる?

Do you know who Tom’s girlfriend is?

顕微鏡を発明したのは誰だか知ってる?

Do you know who invented the microscope?

あの人たち誰だか知ってる?

Do you know who those people are?