Locating Countries from IP addresses

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1. Converting an IP address to an IP Number

2. Retrieving the Country Name and Country Code from the IP Number

1. Converting an IP address to an IP Number

IP address (IPv4 / IPv6) is divided into 4 sub-blocks. Each sub-block has a different weight number each powered by 256. IP number is being used in the database because it is efficient to search between a range of number in database.

Beginning IP number and Ending IP Number are calculated based on following formula:

IP Number = 16777216*w + 65536*x + 256*y + z     (Formula 1)

where
IP Address = w.x.y.z

For example, if IP address is "202.186.13.4", then its IP Number "3401190660" is based on the Formula 1.

IP Address = 202.186.13.4

So, w = 202, x = 186, y = 13 and z = 4

IP Number = 16777216*202 + 65536*186 + 256*13 + 4
          = 3388997632 + 12189696 + 3328 + 4
          = 3401190660

To reverse IP number to IP address,

w = int ( IP Number / 16777216 ) % 256
x = int ( IP Number / 65536    ) % 256
y = int ( IP Number / 256      ) % 256
z = int ( IP Number            ) % 256

where % is the mod operator and int is return the integer part of the division.


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2. Retrieving the Country Name and Country Code from the IP Number

Search the IP-COUNTRY TABLE to match a unique record that has the IP number fits between From IP Number and To IP Number.

For example, IP Address "202.186.13.4" is equivalent to IP Number "3401190660". It falls in the following range of IP number in the table because it is between the "From IP number" and the "To IP number".

"3401056256","3401400319","MY","MALAYSIA"

From the IP range, the Country Name is Malaysia and Country Code is MY.

IP-COUNTRY TABLE

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Debasis Mohanty

Orissa, INDIA

Email ID: debasis_mohanty@msn.com