Computer Networking Basics
Which correctly describes the role of ARP?
- AIt finds the MAC address of a device on the same network from its IP address
- BIt finds a server's IP address from its domain name
- CIt automatically assigns IP addresses to devices that join the network
Show answer and explanation
Answer: A. It finds the MAC address of a device on the same network from its IP address
In ARP (Address Resolution Protocol), the host that wants to send broadcasts a request saying "whoever has this IP address, tell me your MAC address," and only the matching device replies with its MAC address by unicast. The resulting mapping is kept in the ARP cache for a while and reused. Because Ethernet delivers frames by MAC address, this mapping is needed before an IP packet can be sent. Finding an IP address from a domain name is the job of DNS, and assigning IP addresses automatically is the job of DHCP. IPv6 uses ICMPv6 Neighbor Discovery (NDP) instead of ARP.
- A. Correct. It maps IP addresses to MAC addresses.
- B. That is the role of DNS.
- C. That is the role of DHCP.