Ok, I'm not sure of this. But I thinked that if I want send an arp request to an host, I must specify mac address destination and peraphs its ip address.
I know that in C language is possible forging arp packets. In Net::RawIP I read:
The ARGOFDEST and the ARGOFSOURCE can be given as a string which contain just 6 bytes of the real ethernet address or like the output of the ifconfig(8) e.g. 00:00:E8:43:0B:2A or just an ip address or a hostname of a target, then a mac address will be discovered automatically.