void 
optionToWire(DNSOutput out) {
	out.writeU16(family);
	out.writeU8(sourceNetmask);
	out.writeU8(scopeNetmask);
	out.writeByteArray(address.getAddress(), 0, (sourceNetmask + 7) / 8);
}
Returns the IP address of the client.
src/main/java/core/org/xbill/DNS/ClientSubnetOption.java