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Reply from 14.4.4.4: bytes=32 time=8ms TTL=255

Reply from 14.4.4.4: bytes=32 time=3ms TTL=255

Ping statistics for 14.4.4.4:

Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),

Approximate round trip times in milli-seconds:

Minimum = 3ms, Maximum = 8ms, Average = 4ms

Use the arp a command to view the ARP cache on a Windows machine:

C:\>arp -a

Interface: 10.1.0.99 on Interface 0x1000002

Internet Address Physical Address Type

10.1.0.1 00-50-73-07-92-9c dynamic

10.1.0.2 00-50-73-07-c7-0b dynamic

14.4.4.4 00-50-73-07-c7-0b dynamic

C:\>

Notice that the MAC address for 10.1.0.2 and 14.4.4.4 are the same. Router
A and Router B both replied; however, Router B's packet arrived first.

You can observe the exchange on the router as shown in this output:

RouterB#

IP ARP: rcvd req src 10.1.0.99 0040.0526.d7ee, dst
14.4.4.4 Ethernet0

IP ARP: sent rep src 14.4.4.4 0050.7307.c70b,

dst 10.1.0.99 0040.0526.d7ee Ethernet0

Now let's assume that Router B's Ethernet0 fails and Host C attempts to

ping 14.4.4.4 again. Host C still has Router B's MAC address in the ARP
table for getting to 14.4.4.4. The ping will fail. Now when Host C tries to
ping 14.4.4.4, it gets the following results:

C:\>ping 14.4.4.4

Pinging 14.4.4.4 with 32 bytes of data:

www.sybex.com