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Address Resolution Protocol (ARP)

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An IP address is the logical addressing scheme for nodes on a network. IP Addresses exist at the Network layer of the OSI Model and help facilitate the L3 goal of “end to end” delivery. A MAC address is the physical addressing scheme for individual NIC cards on each node of a network. MAC addresses […]

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ARP Probe and ARP Announcement

We finally come to the last iteration of ARP that this article series will discuss. They are the ARP Probe and the ARP Announcement. Both of these are used in a process known as Duplicate Address Detection. The idea is if a host acquires and puts to use an IP address that happens to already […]

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Gratuitous ARP

We’ve talked about Traditional ARP, where a node is requesting another node’s MAC address. We’ve also talked about Proxy ARP, where a node is answering an ARP request on behalf of another node. Which brings us to another iteration of ARP known as Gratuitous ARP. A Gratuitous ARP is an ARP Response that was not prompted […]

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Proxy ARP

We’ve discussed the use cases and role of traditional ARP in the prior article of this series. In this article we will discuss Proxy ARP and its role and significance. Proxy ARP occurs when one node is responding to an ARP request on behalf of another node. Proxy ARP is not a malicious event, it […]

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Traditional ARP

As we’ve learned before, the Address Resolution Protocol (ARP) is the process by which a known L3 address is mapped to an unknown L2 address. The purpose for creating such a mapping is so a packet’s L2 header can be properly populated to deliver a packet to the next NIC in the path between two […]