Carrier Grade NAT Design Quiz

1. In Lightweight 4over6 (lw4o6), where is NAT44 translation performed?

At the border gateway router

At the customer premises equipment (CPE)

At the regional access point

At the DNS resolver

2. In a carrier-grade NAT deployment, which metric is most critical for dimensioning the CGN platform?

Number of concurrent NAT sessions and translation throughput

Total customer bandwidth consumption

Number of routers in the network

Average packet size on the network

3. What is the primary purpose of the wellknown prefix 64:ff9b::/96 in NAT64?

To identify IPv4-mapped IPv6 addresses for automatic translation

To reserve addresses for multicast traffic

To allocate addresses for loopback interfaces

To define the management subnet for routers

4. Which of the following is a limitation of CGN that affects real-time applications?

Increased latency due to address translation processing

NAT traversal difficulties for VoIP and gaming applications

Reduced bandwidth capacity

Incompatibility with IPv6 devices

5. In CGN, session affinity is critical for which type of applications?

Stateless protocols like DNS and NTP

Stateful protocols like HTTP and HTTPS

Applications using asymmetric routing and peer-to-peer connections

Only UDP-based applications

6. What is the typical IPv6 prefix length used in NAT64 for well-known prefix?

/32

/48

/64

/96

7. Which CGN deployment requires DNS64 to function properly?

NAT64

DS-Lite

Lw4o6

MAP-E

8. In a CGN architecture, what is the primary function of the Mapping Table?

Records all IPv4 to IPv6 address translations and port mappings

Stores customer billing information

Tracks routing paths through the network

Manages MPLS label distribution

9. What is the key advantage of stateless NAT64 over stateful NAT64?

Requires less memory and scales better on border routers

Supports more concurrent connections

Provides better security against DDoS attacks

Enables bidirectional communication initiation

10. Which protocol is used to provision port sets to lightweight 4over6 clients?

DHCP option 89

DHCP option 88

DHCP option 90

DHCP option 92

11. What is the primary purpose of Carrier Grade NAT (CGN) in service provider networks?

To translate private IP addresses to shared public addresses for multiple customers

To encrypt all traffic between customer sites

To provide firewall protection on the WAN edge

To prioritize voice traffic over data traffic

12. What is the Carrier Grade NAT minimum port reservation per customer called?

Port pool

Port block

Port allocation unit

Port quota

13. Which CGN deployment model assigns unique addresses to each customer but shares ports?

Address sharing

Port sharing

Stateful NAT64

Lightweight 4over6

14. In CGN logging, what information must be retained for legal intercept purposes?

Source IP, destination IP, port mappings, and timestamps

Only source IP addresses

Only port numbers and timestamps

Entire packet payloads

15. What is the primary challenge in designing high-availability CGN systems?

Maintaining session state consistency across redundant NAT devices

Preventing IPv4 address spoofing

Managing IPv6 prefix delegation

Reducing latency in the access network

16. Which mechanism allows IPv6-only clients to communicate with IPv4-only servers in NAT64?

DNS64 and NAT64 translation

IPv6 tunneling protocol

Dual-stack routing

MPLS traffic engineering

17. In a CGN deployment, what is the typical port allocation ratio per customer?

1 port per customer

256-512 ports per customer

1024-2048 ports per customer

65535 ports per customer

18. What is the primary difference between NAT64 and DS-Lite?

NAT64 requires full IPv6 deployment; DS-Lite uses IPv4 as the backbone

DS-Lite is stateless; NAT64 is stateful

NAT64 translates at the customer edge; DS-Lite translates at the provider edge

NAT64 supports only UDP; DS-Lite supports TCP and UDP

19. In DS-Lite, what is the function of the AFTR (Address Family Transition Router)?

Converts IPv6 packets to IPv4 at the customer premises

Performs NAT44 and IPv6 encapsulation/decapsulation for tunneled traffic

Routes IPv6 traffic to IPv4-only data centers

Compresses IPv4 headers for bandwidth optimization

20. Which RFC defines Large-Scale NAT (LSN) architecture for service providers?

RFC 6333

RFC 6144

RFC 6146

RFC 6052

CCIE Service Provider Carrier Grade NAT Design Quiz