The authentication protocol you specify for each pool determines which type of challenges the servers in the pool issue to clients. The available protocols are:

To specify the authentication protocol for Front End Servers

  1. Open the Office Communications Server 2007 R2 snap-in.

  2. In the console tree, expand the forest node, and then do one of the following:

    • For an Enterprise pool, expand Enterprise pools, right-click the pool, click Properties, and then click Front End Properties.

    • For a Standard Edition server, expand Standard Edition servers, right-click the pool, click Properties, and then click Front End Properties.

  3. Click the Authenticationtab.

  4. On the Authenticationtab, in the Authentication protocollist, click the protocol you want to use:

    • Kerberosto have the servers in the pool issue challenges using only Kerberos authentication.

    • NTLMto have the servers in the pool issue challenges using only NTLM.

    • Both NTLM and Kerberosto have the servers in the pool issue challenges using either NTLM or Kerberos authentication, depending on the capabilities of the client.