350-401 Question 195
Select 4A network engineer is tasked with configuring NAT on a Cisco router to allow internal hosts to access the internet using a single public IP address. The router's GigabitEthernet0/0 interface is connected to the internal network with the IP range 192.168.1.0/24, and the GigabitEthernet0/1 interface is connected to the ISP. Which of the following configuration commands correctly implements PAT for this scenario?
- A
ip nat inside source list 1 interface GigabitEthernet0/1 overload
- B
interface GigabitEthernet0/0 ip nat outside
- C
interface GigabitEthernet0/1 ip nat outside
- D
access-list 1 permit 192.168.1.0 0.0.0.255
- E
interface GigabitEthernet0/0 ip nat inside
Show answer and explanation
Correct answers: A, C, D, E
Explanation
To configure NAT with PAT (overload), you need to define the interfaces participating in NAT, create an access control list (ACL) to define the internal IP range eligible for translation, and associate the ACL with NAT using the 'ip nat inside source' command. In this scenario, GigabitEthernet0/0 is the internal interface ('ip nat inside'), and GigabitEthernet0/1 is the external interface ('ip nat outside'). The ACL permits the private IP range (192.168.1.0/24), and the 'ip nat inside source list 1 interface GigabitEthernet0/1 overload' command configures PAT using the ISP-facing interface.
- A. Correct.
Correct: This command configures PAT (Port Address Translation) by associating access list 1 with the GigabitEthernet0/1 interface and enabling address overloading.
- B. Incorrect.
Incorrect: The GigabitEthernet0/0 interface is the internal interface, so it should be configured as 'ip nat inside' instead of 'ip nat outside'.
- C. Correct.
Correct: This command correctly designates the GigabitEthernet0/1 interface, which is connected to the ISP, as the 'ip nat outside' interface.
- D. Correct.
Correct: This access list permits traffic from the internal subnet 192.168.1.0/24 to be translated using NAT.
- E. Correct.
Correct: This command correctly designates the GigabitEthernet0/0 interface, which is connected to the internal network, as the 'ip nat inside' interface.