What is gratituous ARP?

Gratituous Arp.

It helps to detect ip duplicacy in a network.

Gratuitous arp is generated when you assign ip address or the link comes up, Gratituous arp Reply is generated by device automatically.

The gratuitous ARP Reply packet has following characteristics:-

1)Both source and destination IP in the packet are the IP of the host issuing the gratuitous ARP

2)The destination MAC address is the broadcast MAC address (ff:ff:ff:ff:ff:ff)

it means the packet is broadcasted in the network

Assigned IP add on host1  so It generates Gratituous Arp

If Host1 receives reply of gratuitous ARP request thats mean there is an IP address conflict(duplicate) in your network