ARP Protocol

ARP, or Address Resolution Protocol, is a crucial network protocol that facilitates translation between IP addresses and physical addresses (MAC addresses) in a computer network.

What is the ARP Protocol?

When a computer needs to send data to another computer within the same network, it must know its physical address, known as a MAC address (Media Access Control). The ARP protocol translates IP addresses (e.g., 192.168.50.101) into MAC addresses (e.g., 0C-A5-9D-29-15-1B).

How does it work?

When a computer needs to communicate with another device, it first checks its ARP cache, where recent translations of IP addresses to MAC addresses are stored. If there's no record, it broadcasts an ARP request into the network with the IP address of the target device. This request includes the sender's IP address and MAC address. If a device with the matching IP address is present in the network, it replies with an ARP reply containing its MAC address.

Upon receiving the ARP reply, the computer stores the IP-to-MAC address pairing in its ARP cache, a table containing address translation information. This cache is used for faster address translation in future communication with the same device.

Why is it important?

ARP protocol is crucial for proper communication in computer networks. Without it, computers wouldn't be able to deliver data to the correct destination device. Thanks to ARP, we can effectively communicate in networks and leverage the advantages of the modern digital world.

Additional Information

For most users, the ARP protocol is automatically managed by the operating system and doesn't require manual intervention. The operating system automatically performs ARP queries and stores responses in the ARP cache.

Users encounter the ARP protocol in everyday computer network usage, often without realizing it. It's a key element enabling proper communication between devices on the network. I hope this guide helped you better understand the ARP protocol.

Where to Find the ARP Table and Its Information

On any computer, type "cmd" into the search to access the terminal/console.

Type "arp -a".

Here, you'll see information such as Internet Address (IP address), Physical Address (MAC address), and Type.

Type can be either static or dynamic.

• Static - entries are manually added or by the system, devices with which the computer communicates constantly.

• Dynamic - entries are added via ARP requests. The computer can remove them from the cache when it no longer needs to communicate with them.

We can add a static entry ourselves using the command "arp -s [IP address of device] [MAC address of device]".