Configuring DRAS with Reserved IP Addresses for Private Networks

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Article ID: 178538 - View products that this article applies to.
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Per RFC 1597: Section 3: Private Address Space, The Internet Assigned Numbers Authority (IANA) has reserved the following three blocks of the IP address space for private networks: - , -, and -

These network IDs and the associated IP addresses may be used freely in any internal network scheme and will not affect interoperability with the Internet as a whole. In particular, the class C range is the preferred range to use when configuring the async connectors of Microsoft Exchange Server.


Each async interface on a Windows NT Server computer requires two (2) ip address; one for the server and one for the client of the particular session. The network ID of the async interface should be such that the async interface is on a different subnet than the network interface of the server; as such the unit is multihomed. Using a subnet mask of 255 in the third octet of the class C address allows 255 networks with 254 hosts on each network; this facilitates ease of planning and configuration.

For example, connect 3 Exchange sites through the Dynamic Remote Access Service (RAS) connector. Each Exchange Server computer has a single modem.

  1. In the RAS configuration, select a static pool of addresses.
  2. Configure the pools on each server as follows.
          Server_1 and;
          Server_2 and
          Server_3 and
Thus the RAS server session on each server will get the .1 address and the client session will be assigned the .2 address.


Article ID: 178538 - Last Review: October 7, 2013 - Revision: 3.3
  • Microsoft Exchange Server 4.0 Standard Edition
  • Microsoft Exchange Server 5.0 Standard Edition
  • Microsoft Exchange Server 5.5 Standard Edition
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