From the course: Wireshark Essential Training

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Understand ARP

Understand ARP

- [Instructor] On a local area network, the data link layer uses the MAC address of the destination machine rather than the IP address. Address Resolution Protocol resolves an IP address to a MAC address on a local area network. Let's take a look at where ARP resides in the OSI model. It resides in between layer three and layer two. And that's because when we take a look at it, it doesn't have a network layer header, it doesn't have a transport layer header, it's simply doing a resolution. In addition to the ARP request, ARP replies, you might also see a gratuitous ARP, which is a test for duplicate IP addresses on a local area network. If you'd like to follow along, go to packetlife.net and I selected ARP and this last one here ICMP across dot1Q.cap. I've opened it up in Wireshark and there really aren't a lot of packets in this capture, but we'll just take a look at ARP. We'll put a display filter in and you see…

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