Different types of network address translation are- Static network address translation (NAT), Dynamic, Overloading NAT and Overlapping NAT. Before describing the various types of network address translation, one should know about NAT first. It is a process in which the IP address information is modified into IPv4 headers. Now various type of NAT are discussed below-
* Static NAT- this is the process in which one to one mapping is done between a registered and unregistered IP address. By this process a permanent mapping is put between an internal address and a public network. For example, 192.168.8.50 will always be 192.0.2.75. Static network address translations are used to increase traffic in the web server or mail server.
* Dynamic NAT- these types of network address translation are used when all private IP subnet share an entire pool of public Internet Protocol (IP) addresses. By this process dynamic mapping can be done between private address and a public address. When a private server wants to connect to the web, a public address is selected. This process creates a one to one mapping or relationship on the first come first serve basis. As soon as you initiate a connection, a public IP address is selected and allotted to you. And when you disconnect, the IP address is available for some other user. Next time when you reconnect, you will be allotted some other public address. This is why it is called as dynamic network address translation.
* Overloading Network address translation- among the various other types of network address translation this NAT is also very important to study. It is also known by another name as PAT (Port Address Translation). In this various different internal private addresses may connect to a single public address. Here many unregistered IP addresses are mapped to a registered IP address. This is possible because on the mapping table, the different mappings are placed according to the used source and destination ports. When ports are available to be remapped, many unregistered IP address (private addresses) may connect to a pool of registered IP address (public address) or even a single address.
* Overlapping Network Address Translation- in the process of Overlapping NAT, the internal IP addresses are registered IP addresses and are utilized on some other network. This can even lead to a conflict but to avoid the conflict, mapping table for NAT is built for translation of extra IP addresses to a unique single IP address. This process creates a unique IP address whether the packets are sent or received. It converts and translates internal private addresses to a unique publicly accessible network.
Other than the different types of network address translation you must also know the different types of addresses used in a network- local (refers to what goes on inside the network), global (refers to what goes on outside your network), inside local address, inside global address, outside global address and outside local address.
This is about the various different types of network address translation and their functions.