What does the “Inside Global” address represent in the configuration of NAT?
A.
the summarized address for all of the internal subnetted addresses
B.
the MAC address of the router used by inside hosts to connect to the Internet
C.
a globally unique, private IP address assigned to a host on the inside network
D.
a registered address that represents an inside host to an outside network
Cisco calls the private IP address used in the inside network the inside LOCAL address and the address used to represent the host to the rest of the Internet the inside GLOBAL address
http://www.cisco.com/c/en/us/support/docs/ip/network-address-translation-nat/4606-8.html
Cisco defines these terms as:
Inside local address—The IP address assigned to a host on the inside network. This is the address configured as a parameter of the computer OS or received via dynamic address allocation protocols such as DHCP. The address is likely not a legitimate IP address assigned by the Network Information Center (NIC) or service provider.
Inside global address—A legitimate IP address assigned by the NIC or service provider that represents one or more inside local IP addresses to the outside world.
Outside local address—The IP address of an outside host as it appears to the inside network. Not necessarily a legitimate address, it is allocated from an address space routable on the inside.
Outside global address—The IP address assigned to a host on the outside network by the host owner. The address is allocated from a globally routable address or network space.
These definitions still leave a lot to be interpreted. For this example, this document redefines these terms by first defining local address and global address. Keep in mind that the terms inside and outside are NAT definitions. Interfaces on a NAT router are defined as inside or outside with the NAT configuration commands, ip nat inside destination and ip nat outside source . Networks to which these interfaces connect can then be thought of as inside networks or outside networks, respectively.
Local address—A local address is any address that appears on the inside portion of the network.
Global address—A global address is any address that appears on the outside portion of the network.
Packets sourced on the inside portion of the network have an inside local address as the source address and an outside local address as the destination address of the packet, while the packet resides on the inside portion of the network. When that same packet gets switched to the outside network, the source of the packet is now known as the inside global address and the destination of the packet is known as the outside global address.
Conversely, when a packet is sourced on the outside portion of the network, while it is on the outside network, its source address is known as the outside global address. The destination of the packet is known as the inside global address. When the same packet gets switched to the inside network, the source address is known as the outside local address and the destination of the packet is known as the inside local address.
This image provides an example.