ISC Exam Questions

Which of the following is an extension to Network Addre…

Which of the following is an extension to Network Address Translation that permits multiple devices providing
services on a local area network (LAN) to be mapped to a single public IP address?

A.
IP Spoofing

B.
IP subnetting

C.
Port address translation

D.
IP Distribution

Explanation:
Port address translation (PAT) is an implementation of Network Address Translation. PAT is a mechanism for
converting the internal private IP addresses found in packet headers into public IP addresses and port numbers
for transmission over the Internet. PAT supports a many-to-one mapping of internal to external IP addresses by
using ports.
Incorrect Answers:
A: IP Spoofing does not involve mapping of IP addresses. IP spoofing is the creation of Internet Protocol (IP)
packets with a forged source IP address, with the purpose of concealing the identity of the sender or
impersonating another computing system
B: IP subnetting is the practice of dividing a network into two or more networks.
D: The distribution of IP addresses does not involve mapping of IP addresses.

Harris, Shon, All In One CISSP Exam Guide, 6th Edition, McGraw-Hill, New York, 2013, p. 606