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Difficulty: HardNAT and PAT Implementation

A network security architect is defining address translation policies for a corporate infrastructure. Match each technical network requirement on the left with its corresponding NAT/PAT implementation method on the right.

  • Providing thousands of internal workstation hosts with simultaneous outbound internet access through a single external interface IP address.Port Address Translation (PAT / Interface Overload)
  • Exposing an internal application server at a fixed private IPv4 address to external partners using a permanent public IPv4 mapping.Static 1:1 Network Address Translation
  • Temporarily assigning public IPv4 addresses from a shared pool to internal hosts on a first-come, first-served basis without port multiplexing.Dynamic NAT
  • Redirecting external inbound connections targeting a custom public port (84438443) to an internal web server listening on standard HTTP port 8080.Port Forwarding (Static PAT)

Answer

1. Thousands of hosts sharing a single external IP maps to Port Address Translation (PAT / Interface Overload).
2. Exposing an internal server via permanent public IP mapping maps to Static 1:1 Network Address Translation.
3. Temporarily assigning public IPs from a pool without port multiplexing maps to Dynamic NAT.
4. Redirecting custom public port traffic to an internal web server port maps to Port Forwarding (Static PAT).
The mappings accurately distinguish between Layer 3 IP translation (Static 1:1 NAT and Dynamic NAT) and Layer 4 port translation/multiplexing (PAT and Port Forwarding). Multiple internal hosts sharing one public IP requires PAT (Overload). A fixed public-to-private server mapping requires Static 1:1 NAT. Temporary 1:1 allocation from a public pool without port multiplexing requires Dynamic NAT. Translating an incoming external port to a different internal IP and port requires Port Forwarding.

Step-by-Step Solution

1
Analyze the requirement for outbound internet access for thousands of hosts using a single public IP address.
Identify that port multiplexing (Layer 4 source port tracking) is required to distinguish individual host sessions, pointing to Port Address Translation (PAT/Overload).
A single public IP address can only support multiple concurrent host connections if unique Layer 4 port numbers are assigned to each session flow.
2
Analyze the requirement for a permanent, bi-directional mapping for an internal server.
Identify that a fixed 1:1 relationship is required without port modification, corresponding to Static 1:1 NAT.
External clients must be able to initiate inbound traffic to the internal server at any time using a persistent public IP address.
3
Analyze the requirement for temporary assignment from a public IP pool without port multiplexing.
Identify 1:1 dynamic mapping from an available address block, corresponding to Dynamic NAT.
When port translation is not utilized, each active internal session consumes a dedicated public IP address from the pool for the duration of the communication.
4
Analyze the requirement for mapping incoming traffic on public port 84438443 to internal port 8080.
Identify destination port translation and IP redirection, corresponding to Port Forwarding (Static PAT).
Port Forwarding allows specific incoming external port requests to be translated to a designated internal target host IP and port number.

Key Concept

NAT and PAT Implementation Types and Address Mapping Mechanisms
Estimated Time:2m 0s
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Topics

NAT and PAT Implementation

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