CCIE Security Exam: NAT Types Supporting Bidirectional Traffic Initiation

NAT Types Supporting Bidirectional Traffic Initiation

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Question

Which three NAT types support bidirectional traffic initiation? (Choose three.)

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Explanations

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A. B. C. D. E.

ABD.

NAT (Network Address Translation) is a process of modifying IP address information in the IP packet header while forwarding the packets through a network. There are different types of NAT, which allow the translation of IP addresses, ports, or both.

Bidirectional traffic initiation refers to the ability of both the source and destination hosts to initiate traffic. In other words, both sides of a communication can start a conversation, send packets, and receive responses.

The three NAT types that support bidirectional traffic initiation are:

A. Static NAT: Static NAT is a one-to-one mapping of a public IP address to a private IP address. It allows bidirectional traffic initiation because both the internal and external hosts can initiate communication using their respective IP addresses. However, it can be challenging to scale because it requires a unique public IP address for each internal host.

C. Policy NAT with nat/global: Policy NAT is a type of NAT that allows the translation of IP addresses based on predefined policies or rules. Nat/global refers to the use of two separate NAT rules, one for translation of source IP addresses (nat) and one for translation of destination IP addresses (global). This allows bidirectional traffic initiation because both the internal and external hosts can initiate communication using their respective IP addresses, which are translated based on the predefined policies.

D. Static PAT: Static PAT (Port Address Translation) is a type of NAT that maps a single public IP address and a specific port to a private IP address and port. It allows bidirectional traffic initiation because both the internal and external hosts can initiate communication using their respective IP addresses and port numbers, which are translated based on the static PAT mapping.

The two NAT types that do not support bidirectional traffic initiation are:

B. NAT exemption: NAT exemption is a process of allowing traffic to bypass NAT and use the original IP addresses. It is typically used for traffic that requires end-to-end connectivity, such as VPN or tunnel traffic. NAT exemption does not support bidirectional traffic initiation because the translated IP addresses are not used for communication.

E. Identity NAT: Identity NAT is a type of NAT that does not perform any translation but rather changes the security level of the IP addresses. It is typically used for traffic that needs to traverse different security zones. Identity NAT does not support bidirectional traffic initiation because it does not perform any translation of IP addresses or port numbers.