HTTP/1.1 401 Unauthorized

[narasimha reddy]

Hi Team i am getting the below issue frequently,could you please do
the need full to resolve this issue .it is very urgent for me.here we
are using Silverlight+wcf+Sharepoint.

HTTP/1.1 401 Unauthorized
Content-Type: text/html; charset=utf-8
Server: Microsoft-IIS/7.0
SPRequestGuid: 9fb145b4-faa7-42b5-bf29-67521b029108
WWW-Authenticate: NTLM
X-Powered-By: ASP.NET
MicrosoftSharePointTeamServices: 14.0.0.4762
Date: Thu, 05 Jan 2012 11:31:44 GMT
Content-Length: 16
Proxy-Support: Session-Based-Authentication



Regards,
Bala

[EricLaw]

The below isn't an "issue", it's a demand for NTLM credentials. You
should see two such responses for every connection you make to a
server which is configured to perform NTLM/Windows authentication. The
client will (generally) reply with a new request bearing an
Authorization header containing an encrypted response to the server's
credential challenge.

Now, if the client *doesn't* automatically send a followup request,
that means that it's not configured to authenticate to the server.
That can happen, for instance, if the server isn't in a security zone
(e.g. Internet) where authentication is automatically permitted (e.g.
Intranet). See http://blogs.msdn.com/b/fiddler/archive/2010/11/22/fiddler-and-silverlight-cross-zone-cross-domain-requests.aspx
for discussion.