NAT Inside command CCNA practice question

[Mike Hagans]

Hey guys,

I was taking a practice CCNA exam and had a question on NAT. I was just curious if anyone could help clarify if this is the correct answer and why?

The question was on how many interfaces of R1 need the "ip nat inside" command to grant external internet access to the entire network. I've attached a screen shot but, the topology was R1 with 4 ports. FA0/1 - 3 and a s0/0/0 port. the s0/0/0 port was going out to the ISP. The other three ports each had a switch and some pc's connected...

My answer was the command would need to go on the 3 Fast Ethernet ports... but the answer was all 4 ports.

Would anyone be willing to shed some light on this?

Thanks again, hoping to take the exam soon.

[paul driver · Accepted solution]

hello

if your next hop of ser0/0 is to an isp (public addtessing) then yes i would agree with you.

unfortunately i am not able to see your topology to check .

res
paul


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[Mike Hagans]

Thats what I was thinking... Maybe the answer was wrong... Oh well thanks.

[MatthewW98]

Actually, I believe the question is correct. Int fa0/1 has 2 sub interfaces and those both need to be configured with nat inside, not just fa0/1. So, there is technically 3 ports (that are the inside network), but there is 4 interfaces because of the the 2 sub interfaces.