Explain IPv6 addressing scheme and the role of the default gateway.

• A. IPv6 uses 64-bit addresses; the default gateway is the DNS server.
• B. IPv6 uses 256-bit addresses; the default gateway is the broadcast address.
• C. IPv6 uses 32-bit addresses; the default gateway is the host's own address.
• D. IPv6 uses 128-bit addresses; the default gateway is the next-hop router learned via RA/RS or configured as the IPv6 router address.

Answer: (D)

IPv6 addresses are 128 bits long, giving a huge address space for devices. On an IPv6-enabled network, a host can auto-configure its own address using mechanisms like SLAAC (often with a network prefix advertised by routers) or DHCPv6. To send traffic beyond the local network, the host needs a default gateway, which is the next-hop router’s IPv6 address on the same link. This gateway address is learned automatically through Router Advertisements and Router Solicitations, or it can be configured manually. When the destination isn’t on the local network, the host forwards the packet to that gateway, which then routes it onward toward the destination. The default gateway’s address is typically the router’s interface address on the local network, and the default route is conceptually the route to any destination (::/0). Note that the DNS server is a separate service and not the gateway used for forwarding packets.