Have you ever discovered that you new a phone number of some one but had forgotten his or her name and other pertinent details? Today search giants like google offer something that is called a reverse lookup service. You enter any phone number in north America and the engine finds the details for you. Convenient? Not only that but the Internet has given birth to thousands of white and yellow pages. Where reverse lookup is available.

Reverse lookup is used by business's to look up old customers, verify current ones and make sure of their employees. In short, it is used for data verification. This however is not the only feature of reverse lookup. Individuals can locate forgotten classmates and friends through addresses e mails or just telephone numbers.

Services like that offered by google search engine, info space and 411.ca in Canada make it a very simple thing to search for different criteria through reverse lookup.

Is it useful? Reverse lookup is a very useful feature offered by today's electronic white and yellow pages. It not only makes life easier for individuals, it also helps business's an opportunity to examine and classify their customers and employees.

With IP spoofing occurring more and more everyday, it has become imperative that a machine requesting for some crucial services goes through a process of reverse look up to establish its identity.

How will this happen? The request arrives in a packet with an IP address indicating the point of origin. The server queries name service on the net to find out what host name is associated with that IP address. The server then queries name service to find out what IP address is associated with that host-name. If this last request fails to find an IP address, or finds one that doesn't match the original, the request for service is rejected. Hence giving security from fraudulent entry and request of services from key providers.

Reverse lookup has been used to create very interesting reverse dictionaries. In an electronic dictionary offering a reverse lookup, you actually search within the definition text. You could search on the words "yellow" and "flower" to find such entries as: abelmoschus, acacia, aconitum...to buttercup...to honey rose, etcetera. In a print version of a reverse dictionary, the reader is taken from a meaning or clue they are aware of to the word they need.

In conventional, alphabetically arranged dictionaries, users have to know the word to read about its meanings. If you don't know the word, you cannot look it up in an alphabetical dictionary! An example of this is: What are the adjectives used for the words "church" (ecclesiastic) or "goat" (hircine, culiciform, capric, caprine)? Think of it, how would you find these in a standard alphabetical

dictionary? In a reverse dictionary, you could look under goat and find, "goat" like a: caprine, hircine, hircinous. Clue or cue words are the words you have in your mind (or tip of your tongue) that lead you to the target words. The compiler has selected the same familiar words that you, the user, would think of when trying to find the target words. The clue/cue words are carefully framed in ways that make the target words readily findable. Though it would

be impractical to provide every possible clue/cue to a target word, a reverse dictionary includes the most probable and generative choices. Even if you have never used a reverse dictionary, you will come to quickly understand what constitutes useful and useless cue/clue words. It is really easy to get the hang of it.

Reverse lookup can be considered as a benefit as well as a weapon. Privacy activists are concerned about revealing the address of a person on just querying for his telephone number. In fact in countries like India, if you have the telephone number of some one, you can not get the address through reverse lookup. However looking at it from another point of view, reverse lookup makes easy to locate important people and business's that can help us in our daily life. It depends how we use this service.