Refer to the exhibit. An engineer is designing a new firewall for an organization and must provision Network Address Translation. This new firewall must support basic Internet access for the…

Question

Exhibits

Options

• AStatic NAT for inbound traffic on port 25
• BDynamic NAT for outbound traffic
• CStatic NAT for outbound traffic on port 25
• DDynamic NAT for inbound traffic
• ENAT overload for outbound traffic
• FNAT overload for inboud traffic on port 25

• A
  75% (21)
• C
  7% (2)
• D
  4% (1)
• F
  14% (4)

Explanation

With only one public IP address, two NAT strategies are needed. For outbound internet access from all internal hosts, NAT overload (PAT-Port Address Translation) is required (E): it maps many private IP addresses to the single public IP by differentiating sessions using unique port numbers. For inbound connectivity to the mail server, a static port-forward using Static NAT on port 25 (SMTP) is required (A): inbound connections on port 25 are statically mapped to the mail server's private IP. Dynamic NAT (B) requires a pool of public IPs and cannot work with a single IP. Static NAT for outbound (C) and Dynamic NAT for inbound (D) do not fit the single-IP, mail-server-hosting scenario. NAT overload for inbound port 25 (F) is essentially what A describes, but Static NAT is the correct and precise term for this mapping.

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