NAT Scenario clarification

[banajahm]

I understand how NAT works and how it is configured on a router but this scenario had me a bit puzzled; let’s say that internally I am using the address space 65.0.0.0 (globally owned by CNN.com) and I am using NAT to translate these addresses to my own global IP address. What if a workstation with the address 65.162.185.1 tries to ping a CNN gateway (which is also 65.162.185.1) or any other node in that owned range? Will the ping go through successfully? Will this be a split horizon issue and there will be no echo replies coming from the destination node? How can this be resolved with out using the well-known private IP address spaces associated with each IP address class?

Thanks

[jamey]

I would think if you ping 65.162.185.1 from your workstation, it would reply since it is its own IP. If your workstation tried to ping another host on 65.162.185.0/24 it wouldn't get to the router to be nat'd because it the destination is local. A lot of it has to do with what subnet mask you are using.

Pinging from workstation 65.162.185.1 (your PC)

1. check to see if ping destination is self

2. check to see if ping destination is on local subnet

If neither of the above steps are true, the ping will go to the default gateway (router).

In short, depending on the way you subnet masks are setup, the ping won't go outside of your local subnet.