Sara, the security administrator, must configure the corporate firewall to allow all public IP
addresses on the internal interface of the firewall to be translated to one public IP address on the
external interface of the same firewall. Which of the following should Sara configure?
A.
PAT
B.
NAP
C.
DNAT
D.
NAC
Explanation:
Port Address Translation (PAT), is an extension to network address translation (NAT) that permits
multiple devices on a local area network (LAN) to be mapped to a single public IP address. The
goal of PAT is to conserve IP addresses.
Most home networks use PAT. In such a scenario, the Internet Service Provider (ISP) assigns a
single IP address to the home network’s router. When Computer X logs on the Internet, the router
assigns the client a port number, which is appended to the internal IP address. This, in effect,
gives Computer X a unique address. If Computer Z logs on the Internet at the same time, the
router assigns it the same local IP address with a different port number. Although both computers
are sharing the same public IP address and accessing the Internet at the same time, the router
knows exactly which computer to send specific packets to because each computer has a unique
internal address.