The IP address is an address having information about how to reach a host (specific host), especially outside the LAN.An IP address is a 32-bit unique address having an address space of 232.The 32 bit IP address is divided into five sub-classes.Class AClass BClass CClass DClass EThe order of bits in first octet determinants the classes of IP address.IPv4 address is divided into two parts.Network IDHost IDDotted decimal notation: Hexadecimal notation: Class A:Network ID is 8 bits longThe host ID is 24 bits long.In IP Class - A addresses, the first byte is reserved for network ids.The higher-order bit of the first octet in class A is always set to zero. The remaining 7 bits in the first octet are used to determine network ID.Class A has total of27 “ 2 = 128 “ 2 = 126 Network ID224 “ 2 = 16777216 “ 2 = 16777214 Host ID[2 address is subtracted because 0.0.0.0 and 127.x.y.z are special address]Default subnet mask for class A is 2555.x.x.x.