[Linux / Centos / Redhat ]
clear arp on interface eth0
#ip neigh flush dev eth0
clear arp on host ip 10.1.1.1
#ip neigh flush 10.1.1.1
Flush arp entry for all hosts in network 192.168.0.0/24
#ip neigh flush 192.168.0.0/24
Flush arp on all entries
#ip neigh flush all