Which protocol is used for IPv4 host discovery?

Which protocol is used for IPv4 host discovery?

• A. Neighbor Discovery Protocol
• B. Dynamic Host Configuration Protocol
• C. Internet Control Message Protocol
• D. Address Resolution Protocol

Answer: (D)

IPv4 host discovery relies on mapping an IP address to a MAC address on the local network, and the protocol that does this is the Address Resolution Protocol. When a host wants to reach another IPv4 host on the same LAN, it broadcasts an ARP request asking, “Who has this IP address? please send me your MAC address.” The device that owns that IP replies with its MAC, and the initiator caches this mapping to send subsequent frames directly. This ARP exchange happens only within the local subnet, since routers don’t forward ARP requests. Other protocols have different roles: IPv6 uses Neighbor Discovery for similar address-to-link-layer mapping; DHCP handles IP configuration rather than discovering other hosts; ICMP is for error reporting and diagnostics.

IPv4 host discovery relies on mapping an IP address to a MAC address on the local network, and the protocol that does this is the Address Resolution Protocol. When a host wants to reach another IPv4 host on the same LAN, it broadcasts an ARP request asking, “Who has this IP address? please send me your MAC address.” The device that owns that IP replies with its MAC, and the initiator caches this mapping to send subsequent frames directly. This ARP exchange happens only within the local subnet, since routers don’t forward ARP requests. Other protocols have different roles: IPv6 uses Neighbor Discovery for similar address-to-link-layer mapping; DHCP handles IP configuration rather than discovering other hosts; ICMP is for error reporting and diagnostics.