LX0-104 · Question #667
In order to discover the link layer address of the device that owns a specific IPv4 or IPv6 address, which mechanism is used?
The correct answer is C. IPv4 uses ARP while IPv6 uses Neighbor Discovery.. IPv4 addresses use ARP for link layer address discovery, while IPv6 addresses utilize the Neighbor Discovery Protocol (NDP) for the same purpose.
Question
Options
- ABoth IPv4 and IPv6 use ARP.
- BBoth IPv4 and IPv6 use Neighbor Discovery.
- CIPv4 uses ARP while IPv6 uses Neighbor Discovery.
- DIPv4 uses Neighbor Discovery while IPv6 uses ARP.
- EBoth IPv4 and IPv6 can use either ARP or Neighbor Discovery depending on the network.
How the community answered
(50 responses)- A6% (3)
- B4% (2)
- C88% (44)
- E2% (1)
Why each option
IPv4 addresses use ARP for link layer address discovery, while IPv6 addresses utilize the Neighbor Discovery Protocol (NDP) for the same purpose.
IPv6 does not use ARP for link layer address resolution; it uses NDP.
IPv4 does not use Neighbor Discovery Protocol (NDP) for link layer address resolution; it uses ARP.
IPv4 uses the Address Resolution Protocol (ARP) to map an IP address to a physical (MAC) address on a local network segment, whereas IPv6 uses the Neighbor Discovery Protocol (NDP), specifically Neighbor Solicitation and Neighbor Advertisement messages, to discover the link-layer address of a node on the same link.
This statement incorrectly swaps the protocols, as IPv4 uses ARP and IPv6 uses NDP.
The mechanisms for link layer address discovery are specific to the IP version (IPv4 vs. IPv6) and are not interchangeable based on network configuration.
Concept tested: IPv4 ARP vs IPv6 NDP
Source: https://www.ietf.org/rfc/rfc791.txt (IPv4), https://www.ietf.org/rfc/rfc4861.txt (NDP)
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