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Event ID 11 — RADIUS Client Configuration

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Applies To: Windows Server 2008

RADIUS clients, also called network access servers, must be configured correctly in Network Policy Server (NPS). RADIUS clients send connection requests and accounting messages to NPS for authentication, authorization, and accounting.

Event Details

Product: Windows Operating System
ID: 11
Source: NPS
Version: 6.0
Symbolic Name: RADIUS_E_INVALID_CLIENT_ADDRESS
Message: The IP address, %1, of the RADIUS client, %2, is not a valid IP address.

Resolve

Change the configuration of the RADIUS client

This condition can occur under the following circumstances:

  • In the NPS Microsoft Management Console (MMC), a RADIUS client is configured by fully qualified domain name (FQDN) or NetBIOS name rather than by IP address, and NPS has not received a DNS server response to the name resolution query. Without the IP address provided by the name resolution query, NPS cannot contact the RADIUS client.
  • NPS is receiving communication from a RADIUS client that is not configured in the NPS MMC.
  • In the NPS MMC, a RADIUS client is configured by either IPv4 or IPv6 address, but the format of the IP address is incorrect.

To perform this procedure, you must be a member of Domain Admins.

To fix DNS name resolution issues:

  • Use DNS client and server troubleshooting information to diagnose and repair the DNS name resolution issue. For more information, see DNS Server at https://go.microsoft.com/fwlink/?LinkId=110949.
  • In the NPS MMC, configure the RADIUS client with the IP address of the RADIUS client rather than the DNS name.

To configure a new RADIUS client:

  1. Click Start, Administrative Tools, Network Policy Server. The NPS MMC opens.
  2. Double-click RADIUS Clients and Servers.
  3. Right-click RADIUS Clients, and then click New RADIUS client.
  4. Follow the steps in the New RADIUS Client Wizard.

To configure the IP address of a RADIUS client:

  1. Click Start, Administrative Tools, Network Policy Server. The NPS MMC opens.
  2. Double-click RADIUS Server and Clients.
  3. Click RADIUS Clients, and in the details pane, right-click the RADIUS client that you want to configure. Click Properties, and then type an IP address in Address (IP or DNS).

Verify

You can use the following procedure to verify that DNS name resolution errors are resolved. In addition, you can use ping results to verify the RADIUS client configuration in the NPS MMC.

To verify the RADIUS client configuration:

  1. Open Command Prompt.
  2. Using ping.exe, ping the RADIUS client using the RADIUS client name. For example, if the RADIUS client name is NAS-01, type ping NAS-01, and then press ENTER.
  3. If ping can resolve the name of the RADIUS client to an IP address, the DNS name resolution error is resolved, and the ping results match the RADIUS client configuration in the NPS MMC.

RADIUS Client Configuration

Network Policy Server Infrastructure