How to find if NTLM or Kerberos is used from WWW-Authenticate: Negotiate header

Question

I am programming a client application in .Net that communicates with server via HTTP.

I need to set different request buffering options in case of NTLM and Kerberos

Answer 1

You will find answer here.

Short answer is:

1.Capture some successfully authorized request using Fiddler tool.
2.Choose "Inspectors" -> "Headers" tab.
3.Pay attention at "Cookies / Login" section, "Authorization" header.

If the Authorization token begins with "YII" then Kerberos is used, but if it begins with "TlR" then Kerberos is not used.

For example Kerberos:

Authorization: Negotiate YIIVDAYGKwYBE...

Not Kerberos:

Authorization: Negotiate TlRMTVNTUA...