What is DS Proxy?

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What is DS Proxy?..

Answer / ranjeet

In a modern Exchange system, the Global Catalog servers
handle requests for the GAL or a custom address list. They
do so using a special service called the Name Server
Provider Interface, or NSPI.

As shown in Figure 5.26, the DSProxy service on an Exchange
server decides how to handle Outlook clients who need a
place to send their NSPI requests. Figure 26
Figure 5.26 Diagram of DSProxy operation. (Click image for
enlarged view.)

You are reading tip #6 from "15 tips in 15 minutes: Managing
recipients and distribution lists," excerpted from Chapter 5
of the book Learning Exchange Server 2003, published by
Addison-Wesley Professional.

Name Service Provider Interface (NSPI) service

Outlook versions older than Outlook 98 service release 2
send their NSPI requests directly to the home Exchange
server of the user. The DSProxy service exposes an NSPI
interface to handle these requests. The original Exchange
client uses MAPI to do name service lookups. DSProxy handles
these requests, as well.

When an Exchange server receives an NSPI request from a
legacy client, it passes the request to a Global Catalog
server for processing. The Global Catalog server determines
the content of the address list and returns the first few
items to the Exchange server, which forwards the reply to
the legacy Outlook client.

For reasons of security and performance, the Exchange server
does not open or modify either the client's NSPI requests or
the Global Catalog server's replies.