You can clear the arp cache using following commands:
Current arp cache
root@server [~]# arp -n
Address HWtype HWaddress Flags Mask Iface
70.167.140.1 ether 00:00:0C:9F:F0:04 C eth0
Clearing arp cache with verbose
root@server [~]# ip -s -s neigh flush all
70.167.140.1 dev eth0 lladdr 00:00:0c:9f:f0:04 ref 42 used 17/0/65 REACHABLE
*** Round 1, deleting 1 entries ***
70.167.140.1 dev eth0 ref 42 used 0/0/0 INCOMPLETE
*** Round 2, deleting 1 entries ***
*** Flush is complete after 2 rounds ***
Current entries
root@server [~]# arp -n
Address HWtype HWaddress Flags Mask Iface
69.167.140.1 ether 00:00:0C:9F:F0:04 C eth0
You can also delete specific arp entries using the two following command
root@server [~]# arp -d 192.168.1.1
root@server [~]# arp -d 192.168.1.2
Add a static arp entry
root@server [~]# arp -s 192.168.1.10 00:00:93:12:04:57
tested on CentOS release 5.7 (Final)
