Difference between ARP and RARP

ARP and RARP are the LAN (Local Area Network) protocols. A LAN is a fast, fault-tolerant data network that only covers a limited area of land. There are three types of LAN data transmissions unicast, multicast, and broadcast. A single packet is transferred from the source to a destination on the network during a unicast transmission. A single data packet is copied and delivered to a certain group of network nodes as part of a multicast transmission. A single data packet is copied and delivered to every network node as part of a broadcast transmission. Both ARP and RARP use broadcast in request and unicast in response.

ARP and RARP

What is ARP?

ARP stands for Address Resolution Protocol which is a LAN protocol. It is a process that links the Internet Protocol (IP) address to the media access control (MAC) address, often known as a fixed physical machine address in a local area network (LAN).

The Networking layer comes under the OSI (Open Source Interconnection) model. The MAC address also known as the Data link layer 48 bit long is used and it creates and destroys a connection between two devices that are physically connected so that data transfer can occur. Similarly, the IP address length is 32 bits long and is also known as the network layer or the layer in charge of sending data packets across various routers.

Types of ARP

They are divided into different types, namely

Proxy ARP

Proxy ARP is a method for responding to an ARP request for an IP address that is not on the same network as the proxy device. The proxy gives its own MAC address as the destination because it is aware of the traffic's final destination's location.

Reverse ARP (RARP)

The Reverse Address Resolution Protocol (RARP) is a protocol for address discovery that can be used by hosts that are unaware of their IP address.

Inverse ARP (IARP)

IARP uses a MAC address to find an IP address as opposed to ARP, which uses an IP address.

Gratuitous ARP

This ARP is used by hosts on networks as a mechanism to publish or change their IP to MAC addresses and is almost like an administrative procedure. An ARP request to convert an IP address to a MAC address does not trigger gratuitous ARP.

What is RARP?

A TCP/IP protocol called RARP is in charge of converting physical addresses (MAC addresses) into IP addresses. For example, Diskless Workstations have only the MAC address but do not have IP addresses. So using the RARP protocol one can find the IP address via any external source.

We have a RARP server waiting for RARP queries on the same network as the hosts. A table on this server contains a mix of MAC and IP addresses. It searches its table when it receives a RARP request to find the IP address that corresponds to the MAC address in the RARP request packet. The host is then sent a RARP reply by the RARP server. The host is aware of its IP address when it receives the RARP reply.

Difference between ARP and RARP

Basic	ARP	RARP
Definition	The Internet Protocol(IP) address of the host is mapped with MAC address of the client or server.	The MAC address of the server is mapped to the Internet Protocol address of the client.
IP Address	ARP will help to find the IP address of the different systems.	RARP will help to find the IP address of the same system.
Maintenance	The ARP table is maintained or managed by the local host.	The RARP table is maintained or managed on the server side.
LAN Transmission	A Broadcast MAC address is used.	A Broadcast IP address is used.
Purpose	It is used to get the Machine address of a system using its Internet Protocol address.	The layer 2 forwarding tables are updated by RARP whenever a MAC address changes data centers.
Common Improvements	We need to maintain a cache of recent translations and the storage space required for these addresses is small. So store the IP and physical addresses of every host that broadcasts ARP. Every host that receives a broadcast ARP request will thereafter be able to determine the sender's address translation.	RARP clients should not be allowed to keep trying. That only results in useless broadcasts and so has one or two RARP backup servers running at arbitrary delays.
Uses	The purpose of ARP involves finding the machine address of the other host.	It is utilized with minimum resources.

Conclusion

Apart from the differences, they also have some similarities, like they both map the Internet Protocol and the Machine address. In LAN for data transmission, the node uses ARP broadcast and RARP unicast. They both come under the third layer of the Open Souce Interconnection(OSI) model which is the network layer.