300-420 Question 59
Select 3An enterprise network is planning to adopt IPv6 while maintaining compatibility with existing IPv4-only systems. To ensure seamless communication between IPv4 and IPv6 networks, what should the design focus on when implementing boundaries for IPv4/IPv6 translations?
- A
Deploy Network Address Translation-Protocol Translation (NAT-PT) at the boundary to facilitate IPv4-to-IPv6 communication.
- B
Implement NAT64 at the boundary to allow IPv6 hosts to communicate with IPv4-only services.
- C
Use DNS64 to synthesize AAAA records for IPv6 hosts querying IPv4-only services.
- D
Enable dual-stack on all devices within the network to eliminate the need for translation boundaries.
- E
Configure SIIT (Stateless IP/ICMP Translation) for stateless IPv4/IPv6 communication.
Show answer and explanation
Correct answers: B, C, E
Explanation
When designing boundaries for IPv4/IPv6 translations, it is crucial to choose modern, scalable mechanisms that ensure seamless communication. NAT64 and DNS64 are widely used and recommended solutions for translating between IPv6 and IPv4 networks, especially when IPv6-only hosts need to communicate with IPv4-only services. SIIT provides a stateless alternative for specific use cases. NAT-PT is outdated and not recommended, and dual-stack, while effective, is not a translation mechanism and requires full IPv4 and IPv6 deployment, which may not always be practical.
- A. Incorrect.
NAT-PT is deprecated by IETF due to scalability and operational issues. It is not recommended for modern IPv4/IPv6 translation implementations.
- B. Correct.
NAT64 provides a stateful mechanism for translating IPv6 traffic into IPv4, enabling communication between IPv6-only and IPv4-only networks.
- C. Correct.
DNS64 works alongside NAT64 by synthesizing AAAA records, allowing IPv6-only hosts to resolve and communicate with IPv4-only services.
- D. Incorrect.
While dual-stack eliminates the need for translation boundaries, it requires both IPv4 and IPv6 to be implemented across the entire network, which might not be feasible in all scenarios.
- E. Correct.
SIIT offers stateless IPv4/IPv6 communication, which is efficient for certain use cases such as translation of ICMP or small-scale stateless environments.