Most IP addresses are public, in the sense that they can appear on the public Internet. However, a few IP addresses have been designed as private IP addresses. One private IP address range is 172.16.0.0 to 172.31.255.255. Private IP addresses can only appear within a firm. In Figure 6-21, internal hosts have private IP addresses except for those in the DMZ, which use public IP addresses. Explain this discrepancy if you can.