NAT/PAT Interface Configuration Question

eitherway

This is a review question I got on a practice test for ICND1.

When setting up NAT on this router, to which interface should it be applied? Based on the diagram it looked like it should be applied on interface G1/0, but apparently that's wrong and it should be applied to interface G2/0. I must be missing something, because I don't understand how you can be applying the ACL and NAT configuration to an interface that isn't even on the router. Please explain!

Thank you in advance.

TechGuru80

G2/0 is clearly there but kind of small at the top by the internet. NAT would always be on that interface...not going into a network. First you have to have an access list to use for NAT. When we look at the two options creating an ACL: list two would only allow 172.16.0.x addresses...we lose the 172.16.50.x network...automatically this is wrong and anything with ACL #2 is wrong. From there you just need to pick the correct interface, which is G2/0.

NAT commands are basically: internally with this criteria going out of this interface (overload for PAT). That show command is also done on R2.

All of your internal traffic should get summarized into one NAT address before going to the internet.

eitherway

Ah...I see, I was looking at the wrong g2 interface. It all makes sense now, I guess I need to read the questions more carefully.