Reverse lookup is a procedure of using a
value to retrieve a
unique key
In relational database management systems, a unique key is a candidate key. All the candidate keys of a relation can uniquely identify the records of the relation, but only one of them is used as the primary key of the relation. The remaining candi ...
in an
associative array
In computer science, an associative array, key-value store, map, symbol table, or dictionary is an abstract data type that stores a collection of (key, value) pairs, such that each possible key appears at most once in the collection. In math ...
.
Applications of reverse lookup include
*
reverse DNS lookup
In computer networks, a reverse DNS lookup or reverse DNS resolution (rDNS) is the querying technique of the Domain Name System (DNS) to determine the domain name associated with an IP address – the reverse of the usual "forward" DNS lookup o ...
, which provides the domain name associated with a particular IP address,
*
reverse telephone directory
A reverse telephone directory (also known as a gray pages directory, criss-cross directory or reverse phone lookup) is a collection of telephone numbers and associated customer details. However, unlike a standard telephone directory, where the user ...
, which provides the name of the entity associated with a particular telephone number,
[.]
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reverse image search
Reverse image search is a content-based image retrieval (CBIR) Query string, query technique that involves providing the CBIR system with a sample image that it will then base its search upon; in terms of information retrieval, the sample image i ...
, which provides similar images to the one provided.
See also
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Inverse function
In mathematics, the inverse function of a function (also called the inverse of ) is a function that undoes the operation of . The inverse of exists if and only if is bijective, and if it exists, is denoted by f^ .
For a function f\colon ...
*
Reverse dictionary
References
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Arrays