From: thedeerhunter1978@movie.uni   
      
   I have two Linux hosts, X and Y.   
      
   X sends a "broadcast" gratuitous (aka unsolicited) ARP request to Y,   
   hoping that Y will refresh its ARP cache:   
      
       X> arping  -b  -I eth0  -U     
      
      
   Y does receive the ARP request (I verified this with wireshark), and   
   the ARP request does contain all the proper information (MAC and IP of   
   X), but Y does not update its ARP cache.  I verified this by running:   
      
       Y> arp -n   
      
   and   
      
       Y> ip neigh show   
      
      
   However, this DOES work if X uses a non-broadcast gratuitous ARP   
   request (no "-U" option):   
      
       X> arping  -b  -I eth0  -s      
      
      
   In this scenario, Y does update its ARP cache.  However, I cannot use   
   this scenario because X does not know about Y (Y is one of many   
   neighbours).  I have to use broadcast gratuitous ARPs.   
      
   Does anyone know why Y will not update its ARP cache when receiving a   
   broadcast gratuitous ARP request?  Thanks much.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)