- A
NAT64 translates IPv6 packets to IPv4 packets and vice versa, allowing IPv6-only clients to access IPv4 servers.
Correct because NAT64 performs protocol translation between IPv6 and IPv4, enabling communication between IPv6-only and IPv4-only hosts.
- B
NPTv6 (Network Prefix Translation) translates the IPv6 prefix of a packet while preserving the host portion of the address.
Correct because NPTv6 is a stateless prefix translation that changes the network prefix but keeps the interface identifier unchanged.
- C
NAT64 requires a DNS64 server to synthesize AAAA records from A records for IPv6 clients.
Correct because DNS64 is typically used with NAT64 to map IPv4 addresses to IPv6 addresses so that IPv6 clients can resolve domain names.
- D
NPTv6 provides port address translation similar to PAT in IPv4 NAT.
Why wrong: Incorrect because NPTv6 is stateless and does not perform port translation; it only translates prefixes, not ports.
- E
Both NAT64 and NPTv6 require stateful inspection of all traffic flows.
Why wrong: Incorrect because NAT64 is stateful (tracks sessions), but NPTv6 is stateless and does not maintain session state.
350-401 NAT and DHCP Practice Question
This 350-401 practice question tests your understanding of nat and dhcp. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which three statements about NAT64 and NPTv6 are true? (Choose three.)
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
NAT64 translates IPv6 packets to IPv4 packets and vice versa, allowing IPv6-only clients to access IPv4 servers.
This question tests understanding of IPv6 transition mechanisms, specifically NAT64 and NPTv6, including their differences and use cases.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
NAT64 translates IPv6 packets to IPv4 packets and vice versa, allowing IPv6-only clients to access IPv4 servers.
Why this is correct
Correct because NAT64 performs protocol translation between IPv6 and IPv4, enabling communication between IPv6-only and IPv4-only hosts.
Related concept
Authentication checks who the user is.
- ✓
NPTv6 (Network Prefix Translation) translates the IPv6 prefix of a packet while preserving the host portion of the address.
Why this is correct
Correct because NPTv6 is a stateless prefix translation that changes the network prefix but keeps the interface identifier unchanged.
Related concept
Authentication checks who the user is.
- ✓
NAT64 requires a DNS64 server to synthesize AAAA records from A records for IPv6 clients.
Why this is correct
Correct because DNS64 is typically used with NAT64 to map IPv4 addresses to IPv6 addresses so that IPv6 clients can resolve domain names.
Related concept
Authentication checks who the user is.
- ✗
NPTv6 provides port address translation similar to PAT in IPv4 NAT.
Why it's wrong here
Incorrect because NPTv6 is stateless and does not perform port translation; it only translates prefixes, not ports.
- ✗
Both NAT64 and NPTv6 require stateful inspection of all traffic flows.
Why it's wrong here
Incorrect because NAT64 is stateful (tracks sessions), but NPTv6 is stateless and does not maintain session state.
Common exam traps
Common exam trap: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
- Authentication checks who the user is.
- Authorization controls what the user is allowed to do after login.
- Privilege levels affect access to EXEC and configuration commands.
- AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
- Do not assume successful login means full administrative access.
- Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
- Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related 350-401 questions on access control and AAA configuration.
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FAQ
Questions learners often ask
What does this 350-401 question test?
NAT and DHCP — This question tests NAT and DHCP — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: NAT64 translates IPv6 packets to IPv4 packets and vice versa, allowing IPv6-only clients to access IPv4 servers. — This question tests understanding of IPv6 transition mechanisms, specifically NAT64 and NPTv6, including their differences and use cases.
What should I do if I get this 350-401 question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related 350-401 questions on access control and AAA configuration.
What is the key concept behind this question?
Authentication checks who the user is.
About these practice questions
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Last reviewed: Jun 18, 2026
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