In order to respond to the lack of IP addresses with the IPv4 protocol, the process of NAT was developed. It is said to use a routable IP address to connect all of a network’s machines by translating, at the Internet gateway, between the internal (non-routable) address of the machine that wants to be connected and the gateway’s IP address.
Definition: Network Address Translation (NAT) is the process of modifying IP address information in IP packet headers while in transit across a traffic routing device. It is an Internet standard which enables a local-area network (LAN) to use one set of IP addresses for internal traffic and a second set of addresses for external traffic.
Three main purposes are served by NAT:
A type of firewall is provided by hiding internal IP addresses
A company is enabled to use more internal IP addresses. Since they’re used internally, there’s no possibility of conflict with IP addresses used by other companies and organizations
A company is also allowed to combine multiple ISDN connections into a single Internet connection
A NAT table that does the global-to-local and local-to-global IP address mapping is created by network administrators. NAT can also be used in conjunction withpolicy routing. NAT can be statically defined or it can be set up to dynamically translate from and to a pool of IP addresses.
