> What is NAT?

Option (A) NAT : Network Address Translation

a) Network Address Translation .................................................................

answer is network address translation

Network Address Terminal..............

a) Network Address Translation 

Basm allah alrahman alrahim

We all use Private address in home , work like192.168.1.3

In the Internet addressing architecture, a private network is a network that uses private IP address space, following the standards set by RFC1918 for Internet Protocol Version4 (IPv4), and RFC4193 for Internet Protocol Version6 (IPv6). These addresses are commonly used for home, office, and enterprise local area networks (LANs)

the private address changed to real address via NAT [ RFC1631 ]

In computer networking, network address translation (NAT) is a technique of modifying the network address information in the IP packet headers while transferring the packet across a traffic routing device; such a technique remaps a given address space into another address space. This allows multiple computers to share a single public IP address, which has become necessary because there are not enough IP addresses for every computer in the world.Today, NAT is used to hide networks (called network masquerading) or to hide IP (called IP masquerading). Masquerading is the mechanism that hides an entire address space, usually consisting of private network addresses (RFC1918), behind a single IP address usually in the public domain address space

For more Information read this  CISCO academy article