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Difficulty: MediumNAT and PAT Implementation

A logistics company is connecting 8080 handheld scanner devices on a warehouse subnet (172.16.10.0/24172.16.10.0/24) to a cloud inventory management platform. The ISP has assigned a single usable public IPv4 address (198.51.100.45198.51.100.45) to the warehouse router's external interface. During testing, technicians observe that only one handheld scanner can access the cloud platform at any given time, while outbound connections from all other devices fail. Inspection reveals the router was configured with standard dynamic NAT without port mapping. Which configuration change should the network technician make to enable all 8080 scanners to communicate over the internet simultaneously?

  1. Enable Port Address Translation (PAT) / NAT Overload on the router to map multiple internal private IP addresses to the single public IP address using unique Layer 4 source port numbers.Answer
  2. B
    Configure a Static NAT mapping for each scanner device private IP address to a distinct public IP address reserved in the local host table.
  3. C
    Rebind outbound HTTP and HTTPS sessions to Layer 2 MAC addresses on the router interface to bypass IP-level transport layer port restrictions.
  4. D
    Modify the WAN interface encapsulation to convert Layer 3 IP packets into Layer 2 frames prior to address translation.

Answer

Enable Port Address Translation (PAT) / NAT Overload on the edge router so that all internal devices share the single public IPv4 address by differentiating connections via unique Layer 4 source port numbers.
Enabling Port Address Translation (PAT), also known as NAT Overload, modifies the router behavior to append a unique Layer 4 source port to each outgoing session. This allows up to tens of thousands of concurrent TCP/UDP sessions from multiple internal hosts (172.16.10.0/24172.16.10.0/24) to be multiplexed over a single public IPv4 address (198.51.100.45198.51.100.45).

Step-by-Step Solution

1
Analyze the network requirement and constraints.
Identified 8080 internal hosts needing simultaneous outbound internet connectivity with only 11 public IPv4 address available.
Standard Dynamic NAT assigns public IP addresses from a pool on a one-to-one basis for active sessions, causing pool exhaustion when only one public IP exists.
2
Evaluate NAT technology types.
Port Address Translation (PAT) allows many-to-one translation by dynamically assigning unique source port numbers (Layer 4) to each session.
PAT tracks individual socket connections (Private IP + Source Port →\rightarrow Public IP + Translated Port), enabling thousands of simultaneous connections over a single public address.
3
Select the proper configuration fix.
Configuring PAT (NAT Overload) resolves the single-device restriction and allows all 8080 handheld devices outbound connectivity.
PAT satisfies the requirement of sharing one public IPv4 address across multiple private hosts.

Key Concept

Port Address Translation (PAT) / NAT Overload
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Topics

NAT and PAT Implementation

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