[[Edited 11th, 13th, 15th January, 2010]]
To specify an IP address in a registry value, there are usually two ways:
The dotted notation is just a convention to make life easier for humans and can only be used in String values. Here the IPv4 address is broken down into four separate bytes; the contents of each byte are expressed as a decimal value and the four decimal values are written down separated by periods (most significant byte first).
A DWORD, though, expects a 32-bit integer. To demonstrate how to derive an integer from a human-friendly-format address: 192 = 0xC0 (this is the most significant byte) 16 = 0x10 1 = 0x01 20 = 0x14 (this is the least significant byte) This would become the integer value 0xC0100114 that you then enter into the registry.
Note - You can also write a little app to call the inet_addr() function to convert a string in dotted notation into a long word.