reverse lookup

Reverse lookup is a procedure of using a value to retrieve a unique key in an associative array.{{citation|title=Think Python|first=Allen|last=Downey|publisher=O'Reilly Media|year=2012|isbn=9781449330729|page=125|url=https://books.google.com/books?id=1mZtP9H6OMQC&pg=PA125}}.

Applications of reverse lookup include

• reverse DNS lookup, which provides the domain name associated with a particular IP address,{{citation|title=Understanding Directory Services|first1=Beth|last1=Sheresh|first2=Doug|last2=Sheresh|publisher=Sams Publishing|year=2001|isbn=9780672323058|page=237|url=https://books.google.com/books?id=CY98qQNHOl4C&pg=PA237}}.
• reverse telephone directory, which provides the name of the entity associated with a particular telephone number,{{citation|title=Naked in Cyberspace: How to Find Personal Information Online|first=Carole A.|last=Lane|publisher=Information Today, Inc.|year=2002|isbn=9780910965507|page=144|url=https://books.google.com/books?id=G62_mWAGdgMC&pg=PA144|author-link=d:Q110453962}}.
• reverse image search, which provides similar images to the one provided.