Cognizant is an American multinational corporation that provides IT services, including digital, technology, consulting, and operations services. It is headquartered in Teaneck, New Jersey, United States. Cognizant is listed in the NASDAQ-100 and the S&P 500 indices. It was founded as an in-house technology unit of Dun & Bradstreet in 1994, and started serving external clients in 1996.
Dun & Bradstreet is the IT service division of the Cognizant corporation.  
It was the other way around. Cognizant was originally the in house IT services division of Dun & Bradstreet.  