ARP (Address Resolution Protocol) primarily operates at Layer 2 (data link layer) of the OSI model and is responsible for resolving IP addresses to MAC addresses within a local network segment. It does not strictly correspond to either Layer 3 or Layer 4 but is essential for facilitating communication between devices on the same network.
The four types of ARP include:
- ARP Request: Sent by a device to request the MAC address corresponding to a known IP address.
- ARP Reply: Sent by a device in response to an ARP request, providing its MAC address.
- Reverse ARP (RARP): Used by diskless workstations or similar devices to obtain their IP address from a network server.
- Inverse ARP (InARP): Used in ATM networks to map between Layer 2 ATM addresses and Layer 3 IP addresses.
An ARP message typically consists of four main address fields:
- Sender Hardware Address: The MAC address of the sender of the ARP message.
- Sender Protocol Address: The IP address of the sender of the ARP message.
- Target Hardware Address: The MAC address of the intended recipient of the ARP message.
- Target Protocol Address: The IP address for which the sender is seeking the MAC address.
Different types of ARP refer to variations in how ARP is implemented or used in different network environments or protocols. These variations include standard ARP for IPv4 networks, ARP for IPv6 networks, Proxy ARP (where a device responds to ARP requests on behalf of another device), and Gratuitous ARP (used to update ARP tables in other devices without a request).
“ARP 4” as a specific term is not widely recognized in networking contexts. However, in general networking terminology, ARP operates primarily at Layer 2 (data link layer) of the OSI model, facilitating communication between devices on the same network segment by resolving IP addresses to MAC addresses. This function is crucial for ensuring that data packets are correctly delivered between devices within a local network, enhancing the efficiency and reliability of network communications.