N10-009 Question 225
Single answer3.4 Given a scenario, implement IPv4 and IPv6 network services.A company is migrating a branch office to IPv6 while keeping IPv4 available for legacy applications. The network team wants client devices to automatically receive IPv6 addresses, the default gateway, and DNS server information without requiring manual configuration. They also want to avoid using stateful DHCPv6 address assignment if possible. Which solution should the technician implement?
- A
Configure SLAAC with ICMPv6 router advertisements and enable stateless DHCPv6 for DNS information
- B
Configure APIPA on all clients and use DHCPv6 only for the default gateway
- C
Configure stateful DHCPv6 to provide addresses, because IPv6 clients cannot learn a default gateway any other way
- D
Configure NAT64 so clients can automatically receive IPv6 addressing parameters from the IPv4 DHCP server
Show answer and explanation
Correct answer: A
Explanation
The best answer is to use SLAAC with ICMPv6 Router Advertisements and stateless DHCPv6. In IPv6, routers advertise network information using ICMPv6 Neighbor Discovery, including the on-link prefix and default gateway. Hosts can then self-configure addresses through SLAAC. If additional information such as DNS servers is needed without centrally assigning addresses, stateless DHCPv6 is the recommended approach. This is consistent with standard IPv6 implementation practices described in IETF specifications such as RFC 4861 for Neighbor Discovery and RFC 4862 for Stateless Address Autoconfiguration. A common misconception is that DHCPv6 supplies the default gateway the way DHCP does in IPv4; in IPv6, the default gateway is normally learned from router advertisements.
- A. Correct.
Correct. In IPv6, Stateless Address Autoconfiguration (SLAAC) uses ICMPv6 Router Advertisements (RAs) to allow hosts to automatically generate their own IPv6 addresses and learn the default gateway. However, SLAAC alone does not reliably provide DNS server information in many Network+ contexts, so stateless DHCPv6 is commonly added to supply DNS and other optional parameters without assigning the actual IPv6 address. This matches the requirement to avoid stateful DHCPv6 address assignment while still automatically configuring clients.
- B. Incorrect.
Incorrect. APIPA is an IPv4 link-local addressing mechanism using the 169.254.0.0/16 range and does not solve IPv6 client configuration requirements. Also, DHCPv6 does not provide the default gateway in normal IPv6 operation; hosts typically learn the default gateway through ICMPv6 Router Advertisements from a router.
- C. Incorrect.
Incorrect. Stateful DHCPv6 can assign IPv6 addresses and other settings, but it is not required here and conflicts with the stated goal of avoiding stateful address assignment if possible. In addition, the claim that IPv6 clients cannot learn a default gateway any other way is false; the default gateway is typically learned through router advertisements, not DHCPv6.
- D. Incorrect.
Incorrect. NAT64 is a translation technology that allows IPv6-only clients to communicate with IPv4-only resources. It is not used to distribute IPv6 addressing, default gateway, or DNS settings from an IPv4 DHCP server. Address autoconfiguration in IPv6 relies on router advertisements and optionally DHCPv6, not NAT64.