ARP vs. RARP — What's the Difference?
By Tayyaba Rehman — Published on January 11, 2024
ARP (Address Resolution Protocol) resolves IP addresses to MAC addresses for local network communication. RARP (Reverse Address Resolution Protocol) maps MAC addresses to IP addresses, mainly for network initialization.
Difference Between ARP and RARP
Table of Contents
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Key Differences
ARP, or Address Resolution Protocol, is a critical protocol used in local area networks (LANs) to map IP addresses to MAC addresses. When a device wants to communicate with another device on the same network, it uses ARP to find out the MAC address corresponding to the IP address of the target device. Conversely, RARP, or Reverse Address Resolution Protocol, works in the opposite manner. It is used to obtain an IP address based on a MAC address, which is particularly useful for network devices that don't have a pre-assigned IP address.
ARP operates primarily for facilitating communication within a network. It ensures that data packets reach the correct physical device by translating the logical IP address into the physical MAC address. RARP, on the other hand, was designed to help diskless computers that boot up without an IP address. These computers use RARP to request an IP address from a RARP server, using their unique MAC address as the identifier.
The functionality of ARP is essential for the normal operation of Ethernet and WiFi networks where IP communication is predominant. Every device that communicates over such networks uses ARP to dynamically resolve IP to MAC address mappings. In contrast, RARP saw limited use and was primarily relevant in environments with diskless workstations or devices that needed network configuration upon boot-up, a need that has largely been supplanted by more advanced protocols like BOOTP and DHCP.
ARP works by broadcasting an ARP request to all devices on the local network. The device with the matching IP address responds with its MAC address, facilitating direct communication. RARP, although similar in operation, sends a request to a RARP server to find out its own IP address. The RARP server, which holds a table of MAC to IP address mappings, responds with the appropriate IP address.
In summary, ARP and RARP are complementary protocols with different purposes. ARP is actively used in almost all modern networks for IP to MAC resolution, making it a fundamental aspect of network communication. RARP, less common in modern networks, played an important role in network initialization for specific types of network configurations and devices.
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Comparison Chart
Purpose
Maps IP addresses to MAC addresses.
Maps MAC addresses to IP addresses.
Use Case
Essential for regular network communication.
Used for network initialization, mainly by diskless devices.
Operation
Sends a broadcast to find the MAC address for a given IP address.
Requests a known server to find the IP address for a given MAC address.
Relevance
Widely used in modern Ethernet and WiFi networks.
Limited use, mostly replaced by DHCP and BOOTP.
Response
Receives a response from the device with the matching IP address.
Receives a response from a RARP server with the IP address mapping.
Compare with Definitions
ARP
ARP operates by broadcasting a request to all network devices.
To connect to the server, the client sent an ARP request to get its MAC address.
RARP
It's used primarily for network initialization of certain devices.
On startup, the legacy system used RARP to determine its network address.
ARP
ARP dynamically updates IP-to-MAC mappings in a network.
With ARP, the network dynamically adapted to the changing IP addresses of mobile devices.
RARP
RARP is used to determine an IP address from a MAC address.
The diskless workstation used RARP to request its IP address upon booting.
ARP
It's essential for routing data packets in Ethernet and WiFi networks.
The network switch used ARP to route the packets to the correct device.
RARP
RARP communicates with a server to resolve MAC addresses to IP addresses.
The booting device sent a RARP request to the server to get its assigned IP address.
ARP
ARP translates IP addresses into MAC addresses for local network communication.
The router used ARP to determine the MAC address of the new laptop on the network.
RARP
RARP has been largely replaced by more advanced protocols like DHCP.
Although the old network used RARP, it was later upgraded to use DHCP for address assignment.
ARP
It facilitates device-to-device communication within the same network.
ARP resolved the IP address to a MAC address, enabling the printer to receive the document.
RARP
It assists diskless devices in acquiring an IP address for network communication.
RARP enabled the networked printer without a hard drive to find its IP address.
Common Curiosities
What is RARP?
RARP is a protocol for obtaining an IP address based on a MAC address, used by network devices.
Why is ARP important in networks?
ARP is essential for normal network operations, enabling devices to communicate with each other on a local network.
When is RARP used?
RARP is used mainly by diskless devices during boot-up to acquire an IP address.
How do devices respond to ARP requests?
Devices with the requested IP address respond to ARP requests with their MAC address.
What type of networks use ARP?
ARP is used in Ethernet and WiFi networks for IP-to-MAC address mapping.
What has replaced RARP in modern networks?
RARP has largely been replaced by DHCP (Dynamic Host Configuration Protocol) and BOOTP (Bootstrap Protocol).
Can ARP be used for remote networks?
No, ARP is designed only for local network communication.
Are ARP and RARP secure?
Both protocols have vulnerabilities and can be subject to security attacks like ARP spoofing.
What is ARP?
ARP is a protocol for mapping IP addresses to MAC addresses in a local network.
How does ARP work?
ARP works by broadcasting a request on the network to find the MAC address corresponding to a specific IP address.
Is RARP still relevant today?
RARP's usage has diminished with the advent of more advanced protocols like DHCP.
Does RARP require a server?
Yes, RARP requires a server to respond to MAC-to-IP address queries.
How do devices use RARP for network initialization?
Devices without an IP address use RARP to request their IP address from a RARP server using their MAC address.
Can ARP resolve external IP addresses?
No, ARP is limited to resolving addresses within the same local network.
What is the primary difference between ARP and RARP?
ARP maps IP addresses to MAC addresses, while RARP does the reverse, mapping MAC addresses to IP addresses.
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Written by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
