> For the complete documentation index, see [llms.txt](https://davidjosearaujo.gitbook.io/online-courses/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://davidjosearaujo.gitbook.io/online-courses/ccna-200-301/dynamic-arp-inspection/gratuitous-arp.md).

# Gratuitous ARP

A *Gratuitous ARP* message is an ARP reply that it sent without receiving an ARP request.

It is sent to the broadcast MAC address.

It allows other devices to learn the MAC address of the sending device without having to send ARP requests.

Some devices automatically send GARP messages when an interface is enabled, IP address is changed, MAC address is changed, etc.

<figure><img src="/files/oP6Yty3u9hNpunURps4t" alt=""><figcaption></figcaption></figure>