What is the purpose of Duplicate Address Detection (DAD) in IPv6?

• A. Detecting duplicate addresses on the network
• B. Ensures two devices do not have the same MAC address
• C. Enables fast re-route between routers
• D. Ensures two devices do not have the same IP address

Answer: (D)

Duplicate Address Detection checks that an IPv6 address is not already in use on the local link before a hostConfigures it. When an interface wants to use a new address, it sends a Neighbor Solicitation for that address. If another node already has the address, that node may respond, letting the requester know the address is in use. If there is no reply, the address is considered unique and can be assigned. This prevents two devices from having the same IPv6 address on the same network segment, which would cause traffic to be misdelivered. DAD is part of the Neighbor Discovery Process and happens on the local link; it does not guarantee global uniqueness and is separate from MAC address uniqueness or routing fast reroute.