ARPARP, which stands for "Address Resolution Protocol," is a protocol used on a local area network to map an IP address to a physical MAC address.
ARP is a program that a computer system uses to determine another computer's MAC address based on its IP address.You might be wondering, "Why do we need MAC addresses?"
The reason is straightforward: any local communications would use MAC addresses rather than IP addresses.
The IP address is used when a computer wants to communicate with another computer on a different network. The IP address is analogous to your mailing address, whereas the MAC address is analogous to your name.
Every computer on a TCP/IP network is assigned an IP address, and some local servers' IP addresses are also assigned to network clients.
You're probably wondering, "How frequently does your computer use ARP?"
To demonstrate how ARP works let’s take an example.
ARP Command Example
A client computer on a local area network attempts to connect to a server. We are discussing communication between two computers on the same broadcast domain, which is a local area network. The client first checks its ARP cache.
ARP cache is a table that contains a list of IP addresses and their corresponding MAC addresses.
To view the ARP table on a Windows computer, open a command prompt and type the following command:
arp –a
The first column is the IP address, and the second column is the MAC address.
The ARP entry is either static or dynamic.
The ARP cache table contains a static ARP entry that is manually added. The ARP program receives dynamic entries.
They will remain there until the ARP cache timeout expires. If no entry for the server is found, the client computer will use ARP to send a message across the entire network.
This is a broadcast message to the local network informing who has the IP address so and so, as well as what your MAC address is.
When a server receives a broadcast message, it responds, "yes, I have that IP address, and here is my MAC address."
Let's go over the ARP Process Step by Step:
1. Because the destination MAC address is a broadcast address, the client sends a broadcast message. Just saying hello! If anyone has the IP address 192.168.1.1, could you please give me your MAC address? , as well as my IP and MAC addresses. Other devices hear the broadcast message and silently discard the ARP packet.When a server hears the message, it sends a unicast message to the client because the destination MAC address and IP address belong to the client.
The client stores the server's MAC address in a cache. Simultaneously, the client updates its cache table for future use.
ARP Summary
It is a layer 2 protocol that locates a layer 2 MAC address using a layer 3 IP address.
Because ARP relies on broadcasting, it operates on a LAN or the same broadcast domain.
It makes use of the ARP table.
ARP Announcements
ARP Announcements are used to "claim" an IP address on the network.
ARP announcement is used to update the ARP tables of other hosts without the need for an ARP request. When a host's IP address has recently changed, it helps to update the network more quickly.
Reverse ARP
A diskless computer with no permanent storage would be unable to find its IP address because IP addresses are stored on the computer's secondary storage.
So, how does a diskless computer get its IP address?
The RARP protocol obtains the computer's internet address by using a physical network address.
The RARP protocol is a network layer protocol that allows any host to obtain its IP address from the server.
The RARP mechanism uses the physical address of the target machine to uniquely identify the processor and broadcast a RARP request. The network server then receives the message, consults the mapping table, and responds to the sender.
When the machine obtains its IP address, it stores it in memory. RARP is not used until the reboot.
In RARP, IP address maintenance is difficult because each server must be configured with a table of static mapping between hardware addresses and IP addresses.
RARP has been superseded by the BOOTP and DHCP protocols.
Inverse ARP
Instead of using layer 3 to find a MAC address, Inverse ARP uses MAC addresses to find IP addresses.
Inverse ARP is simply the inverse of ARP, as the name implies.
It is used in ATM (Asynchronous Transfer Mode) networks for device configuration and is enabled by default.
It is used in frame relay to determine the layer 3 address from the layer 2 address, such as DLCI.
When you configure frame relay, it dynamically maps local DHCP or remote IP addresses. We know the DLCI or remote router but not its IP address when we use inverse ARP.
How to Use ARP
ARP Command is a TCP/IP utility that allows you to view and modify your local Address Resolution Protocol (ARP) cache.
ARP Cache stores recently resolved MAC addresses of network Internet Protocol (IP) hosts.
If you run the ARP command without any arguments, you will see a list of the command's parameters.
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