public static long
increment(long serial) {
	if (serial < 0 || serial > MAX32)
		throw new IllegalArgumentException(serial + " out of range");
	if (serial == MAX32)
		return 0;
	return serial + 1;
}
Increments a serial number.  The number is assumed to be a 32 bit unsigned
integer stored in a long.  This basically adds 1 and resets the value to
0 if it is 2^32.
@param serial The serial number
@return The incremented serial number
@throws IllegalArgumentException serial is out of range
src/main/java/core/org/xbill/DNS/Serial.java