Reverse DNS lookups for IPv4 addresses use the special domain codice_1. In this domain, an IPv4 address is represented as a concatenated sequence of four decimal numbers, separated by dots, to which is appended the second level domain suffix codice_2. The four decimal numbers are obtained by splitting the 32-bit IPv4 address into four octets and converting each octet into a decimal number. These decimal numbers are then concatenated in the order: least significant octet first (leftmost), to most significant octet last (rightmost). It is important to note that this is the reverse order to the usual dotted-decimal convention for writing IPv4 addresses in textual form.