The dàng reading is genuinely rare in modern Chinese - you'll meet it almost exclusively in one fixed compound:
大排挡 (open-air food stall / late-night street eatery, a fixture of Cantonese-speaking cities). Here
挡 is the same root as
档 - 'a slot / arranged stall' - and you'll see both
大排挡 and
大排档 in writing, with
档 now more common in mainland use. For every other meaning, read
挡.
