Question

Difficulty: Very hardNAT and PAT Implementation

Match each Network Address Translation (NAT) implementation concept on the left with its corresponding operational description and traffic mapping behavior on the right.

  • Static NATMaps a single private IP address to a dedicated public IP address permanently, supporting unsolicited inbound connections to internal DMZ servers.
  • Dynamic NATMaps private IP addresses to an available pool of public IP addresses on a first-come, first-served basis without modifying Layer 4 transport ports.
  • Port Address Translation (PAT)Translates multiple private IP addresses to a single public IP address by tracking unique Layer 4 source port numbers for each session state.
  • Static PAT (Port Forwarding)Maps a specific public IP address and destination transport port pair to a specific internal private IP address and service port.

Answer

Static NAT matches the permanent one-to-one IP mapping for DMZ servers. Dynamic NAT matches the pool-based mapping without port alteration. Port Address Translation (PAT) matches many-to-one translation using Layer 4 source ports. Static PAT matches destination port redirection to an internal host and service port.
Each NAT type is accurately paired with its technical execution model: Static NAT provides permanent 1-to-1 IP mapping for unsolicited server access; Dynamic NAT allocates 1-to-1 public IPs dynamically from a pool without port alteration; PAT multiplexes many private IPs to one public IP using Layer 4 source ports; and Static PAT maps targeted public incoming transport ports directly to internal hosts.

Step-by-Step Solution

1
Analyze Static NAT requirements
Identified as a permanent 1:1 Layer 3 mapping between an Inside Local address and an Inside Global address.
Static NAT requires a dedicated public IP for each host and allows bidirectional, unsolicited inbound traffic (e.g., hosting public web servers).
2
Analyze Dynamic NAT operational characteristics
Identified as a dynamic 1:1 allocation from a pool of public IPv4 addresses on demand.
Dynamic NAT does not translate port numbers; sessions are allocated public addresses sequentially until the public pool is exhausted.
3
Analyze Port Address Translation (PAT / NAT Overload)
Identified as many-to-one mapping using transport-layer port tracking.
PAT modifies both IP addresses (Layer 3) and port numbers (Layer 4), storing socket pairs in the state table to allow thousands of internal hosts to share a single public IPv4 address.
4
Analyze Static PAT (Port Forwarding)
Identified as inbound port translation targeting specific internal host services.
Port Forwarding intercepts inbound traffic on a specific public port and forwards it to a private IP and service port destination.

Key Concept

Differentiation of Network Address Translation types (Static NAT, Dynamic NAT, PAT, and Static PAT/Port Forwarding) by Layer 3 vs Layer 4 translation behaviors, pool allocation, and directionality.
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