![](/images/new-backgrounds/1180350/180350173x1.webp)
Multiple Network Address Translation
When addresses are returned to the group of available addresses, they are returned to the head of the group, being the most recently used. If that same host requests a connection an hour later, and the same public address is still available, then it will be mapped to the same private host. If a new host, which has not previously requested a connection, initiates a connection it is allocated the last, or oldest, public address available.
Dynamic NAT is a way of sharing a range of public, or exterior, NAT addresses among one or more groups of private, or interior, hosts. This is intended to provide superior support for applications that traditionally have difficulty communicating through NAT. Dynamic NAT is intended to provide functionality beyond
Static
A common example is a DSL customer’s application. Most DSL ISPs only provide customers with a few IP addresses for use on their network. For networks with more than four or five machines it is usually mandatory to use NAT. A customer may have 15 workstations on the LAN, all of which need Internet access. The customer is only provided five IP addresses by their ISP. The customer has eight hosts, which only need to use email and have Web access, but another seven hosts, which use NetMeeting to communicate with clients once or twice a day. NetMeeting will not work unless a static
The customer can configure four of these addresses to be used for Dynamic NAT. The fifth address is then used for the eight other machines that do not need
WAN Network
Network Address Translation
LAN Network
|
| Available for Dynamic NAT | Used for Normal NAT | |||||||
| 172.16.1.25 | 172.16.1.26 | 172.16.1.27 | 172.16.1.28 |
|
|
| 172.16.1.29 |
|
|
|
|
|
|
192.168.1.2 | 192.168.1.3 | 192.168.1.4 | 192.168.1.5 | 192.168.1.6 | 192.168.1.7 | 192.168.1.8 | 192.168.1.9 | 192.168.1.10 | 192.168.1.11 | 192.168.1.12 | 192.168.1.13 | 192.168.1.14 | 192.168.1.15 | 192.168.1.16 |