Question

You have configured NAT on your router to connect your small company network to the Internet. Shown below is a partial configuration for the router:

hostname RouterA
!
ip address
speed auto
duplex auto
ip nat inside
!
interface FastEthernet0/1
ip address
speed auto
duplex auto
ip nat inside
!
interface Serial0/1/0
ip address
ip nat outside
!
ip nat pool ovrloadd netmask
!
ip nat inside source list 7 pool ovrloadd
!

Following the configuration, you find that no hosts on Fa0/0 or Fa0/1 can connect to the Internet. What should you do so that hosts can connect to the Internet?
1) Configure NAT on Fa0/0 interface
2) Configure NAT on Fa0/1 interface
3) Configure NAT on Serial0/1/0 interface
4) Configure NAT on all interfaces

Answer 1

To enable Internet access for the network, ensure the external interface, Serial0/1/0, is configured with 'ip nat outside'. No changes to Fa0/0 and Fa0/1 interfaces are needed.

Step-by-step explanation:

The issue appears to be with the incorrect application of NAT on the router interfaces. The configuration on both Fa0/0 and Fa0/1 suggests that they have been set with ip nat inside, which is correct as these interfaces connect to the internal network. However, the NAT configuration must also include the external interface which connects to the Internet, typically labeled as ip nat outside in the configuration. Since we have interface Serial0/1/0, this would be our WAN interface and should have ip nat outside applied to it, enabling the translation of internal IP addresses to the single or pool of external IP addresses provided by your ISP for internet access.

To resolve the issue, ensure that the interface connected to the internet, which in this case is Serial0/1/0, is configured with ip nat outside. No changes to the NAT configurations on Fa0/0 and Fa0/1 are necessary. Double-check that the access list referenced by the NAT configuration (in this case, list 7) correctly specifies the internal IP addresses that are permitted to be translated.