In IPv6, explain stateless address autoconfiguration (SLAAC) versus stateful DHCPv6.

• A. SLAAC uses router advertisements to configure addresses automatically; DHCPv6 assigns addresses and/or config information; Stateless means no DHCP server for addresses.
• B. SLAAC uses DHCPv4.
• C. SLAAC requires a DHCPv6 server.
• D. SLAAC is used only for IPv4.

Answer: (A)

IPv6 hosts can learn their configuration in two main ways: SLAAC and stateful DHCPv6. In SLAAC, routers advertise a network prefix using Router Advertisement messages. The host then combines that prefix with its own interface identifier to form an IPv6 address automatically, without relying on a DHCPv6 server to assign the address. For additional settings, the host can derive information from other mechanisms, but the address itself is autoconfigured from the prefix advertised by the router.

In the stateful DHCPv6 approach, a DHCPv6 server is responsible for assigning addresses and can also provide other configuration data such as DNS servers. There is also a stateless DHCPv6 mode, where the server does not assign addresses but may supply other configuration information; the host’s address is still formed or obtained through SLAAC.

So the best fit is: SLAAC uses router advertisements to configure addresses automatically; DHCPv6 assigns addresses and/or config information; Stateless means no DHCP server for addresses. The other choices misstate aspects of IPv6 autoconfiguration—for example, DHCPv4 is not used with IPv6, SLAAC does not require a DHCPv6 server for addresses, and SLAAC is not IPv4-only.