350-401 Question 193
Select 4A network engineer is tasked with configuring Port Address Translation (PAT) on a Cisco router to allow multiple internal devices to share a single public IP address for internet access. The internal network uses the 192.168.1.0/24 subnet, and the external interface is GigabitEthernet0/0. Which of the following steps are required to configure PAT correctly?
- A
Define an access control list (ACL) to identify the internal network traffic.
- B
Configure the 'ip nat inside' command on the internal-facing interface.
- C
Apply the 'ip nat outside' command on the external-facing interface.
- D
Use the 'ip nat inside source static' command to map internal IP addresses to the external IP address.
- E
Use the 'ip nat inside source list' command with the overloaded keyword to enable PAT.
Show answer and explanation
Correct answers: A, B, C, E
Explanation
To configure PAT, the network engineer must define an ACL to identify internal traffic, configure the inside and outside NAT interfaces, and use the 'ip nat inside source list' command with the 'overload' keyword to enable PAT. Static NAT is not applicable in this scenario, as it does not support multiple internal devices sharing a single external IP.
- A. Correct.
Correct: An ACL is required to identify which internal IP addresses will be translated by PAT.
- B. Correct.
Correct: The 'ip nat inside' command is necessary to identify the interface connected to the internal network.
- C. Correct.
Correct: The 'ip nat outside' command is required to identify the interface connected to the external (public) network.
- D. Incorrect.
Incorrect: The 'ip nat inside source static' command is used for static NAT, not PAT. PAT requires dynamic translation with overloading.
- E. Correct.
Correct: The 'ip nat inside source list' command with the 'overload' keyword is used to enable PAT, allowing multiple internal addresses to share a single external IP.