Understanding Network Address Translation

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Understanding network address translation

With network address translation (NAT), you can configure your home network or small office network to share a single connection to the Internet. NAT consists of the following components:

  • Translation component

    The server running Routing and Remote Access on which NAT is enabled translates the IP addresses and TCP/UDP port numbers of packets that are forwarded between the private network and the Internet.

  • Addressing component

    The network address translation computer provides IP address configuration information to the other computers on the home network. The addressing component is a simplified DHCP server that allocates an IP address, a subnet mask, a default gateway, and the IP address of a DNS server. You must configure computers on the home network as DHCP clients in order to receive the IP configuration automatically. The default TCP/IP configuration for computers running any member of the Windows Server 2003 family, Windows XP, Windows 2000, Windows NT, Windows Millennium Edition, Windows 98, or Windows 95 is as a DHCP client.

  • Name-resolution component

    The network address translation computer becomes the DNS server for the other computers on the home network. When name resolution requests are received by the network address translation computer, it forwards the name-resolution requests to the Internet-based DNS server for which it is configured and returns the responses to the home network computer.

For more information about network address translation, see:

For more information about configuring NAT, see Setting Up Network Address Translation.

For an example of using NAT, see SOHO Network to the Internet.


  • Because NAT includes addressing and name resolution components that provide DHCP and DNS services for hosts on the private network, you cannot run:

    • The DHCP service or the DHCP Relay Agent if NAT addressing is enabled.

    • The DNS service if NAT TCP/IP networking name resolution is enabled.