Your network operations team is deploying Access Control Lists (ACLs) across your Internet gateways. They wish to place an ACL inbound on the Internet gateway interface facing the core network (the…

The inside global address is the post-NAT translated address representing an inside host on the public Internet - this address only exists in the packet after NAT translation has occurred on the outside interface, not before.

The outside global address is the real IP address of a remote host on the Internet and would appear as the destination or source of inbound Internet traffic, not as the source of traffic originating from inside hosts.

The inside local address is the IP address assigned to an internal host as it exists on the private network - because the ACL is applied inbound on the core-facing interface, packets arrive at the ACL before the NAT process translates them. This means the source IP field still contains the original, untranslated inside local address, which is what the ACL must reference to match the traffic.

The outside local address is the IP address of an external host as it appears to devices on the inside network - this applies to return traffic from the Internet, not to traffic sourced from inside hosts traversing toward the Internet.