What is IP address “overlapping” as discussed within the context of NAT?
IP address overlapping refers to the situation where a site’s IP address space is already being used by someone else on the Internet. Without special support, the illegally-addressed site will not be able to access the real owners of that address space. The 11.2 Update training slides and the 11.2 NAT documentation (in the 11.2 router configuration guide) give a detailed description of what happens, but it involves intercepting DNS name-query responses from the outside to the inside, setting up a translation for the OUTSIDE address, and fixing up the DNS response before forwarding it onto the inside host.
