Arp
The Address Resolution Protocol is a local-network protocol that maps an IPv4 address to the corresponding link-layer address, typically a MAC address.
Acing the CCNA Exam: Volume 1 Fundamentals and Protocols
ARP is a protocol that resolves an IPv4 address to the MAC address of a host on the local network.
- How it is used
- Uses IPv4-to-MAC resolution to prepare Ethernet frames within a LAN or toward a routed next hop.
- How deep it goes
- Explains request and reply behavior, broadcast flooding, ARP tables, gateways, and per-hop resolution without detailing ARP packet fields.
- Examples
- Uses PC1-to-PC3 LAN resolution, PC1-to-R1 gateway resolution, router next-hop resolution, and R3-to-PC3 delivery.
- What you can do after
- Diagnose frame-delivery behavior by distinguishing ARP-table mappings from switch MAC-table entries and identifying the resolved hop.
Read how Acing the CCNA Exam: Volume 1 Fundamentals and Protocols explains arp →
Acing the CCNA Exam: Volume 2 Advanced Networking and Security
ARP is a network protocol that resolves an IPv4 address to a MAC address on a local network.
- How it is used
- Resolves IPv4 addresses to MAC addresses and frames ARP security as a Dynamic ARP Inspection concern.
- How deep it goes
- Explains message fields, frame encapsulation, exchange steps, poisoning, and Cisco verification, but defers broader protocol detail.
- Examples
- Uses a PC-to-router exchange, broadcast requests, gratuitous replies, poisoned entries, and Cisco DAI command output.
- What you can do after
- Operate/configure DAI, assign trusted ports, verify inspection state, and interpret discarded ARP messages.
Read how Acing the CCNA Exam: Volume 2 Advanced Networking and Security explains arp →
Related concepts
- IP addressuses · An IP address is a numerical address used by the Internet Protocol to identify a network interface and support packet delivery across networks.
- arp tableproduces · An ARP table is a data structure that maps IPv4 addresses to corresponding MAC addresses for local communication.
- arp requesthas part · An ARP request is a broadcast protocol message asking which host uses a specified IPv4 address to provide its MAC address.
- ARP poisoningused by · ARP poisoning is a network attack that sends forged ARP messages to associate an attacker-controlled device with another device’s IP address.
- mac addressproduces · A MAC address is a link-layer identifier assigned to a network interface for communication over a local network link.
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