F5 BIG-IP LTM Specialist: Maintain and Troubleshoot — Question 103

A client is attempting to log in to a web application that requires authentication. The following HTTP headers are sent by the client:

GET /owa/ HTTP/1.1 -
Authorization: Basic dXNlcm5hbWU6cGFzc3dvcmQ=

User-Agent: curl/7.26.0 -

Host: 10.0.0.14 -
Accept: */*

Accept-EncodinG. gzip,deflate -
The web server is responding with the following HTTP headers:

HTTP/1.1 401 Unauthorized -

Content-TypE. text/html -

Server: Microsoft-IIS/7.5 -

WWW-AuthenticatE. NTLM -
DatE. Wed, 16 Aug 1977 19:12:31 GMT

Content-LengtH. 1293 -
The client has checked the login credentials and believes the correct details are being entered.
What is the reason the destination web server is sending an HTTP 401 response?

Answer options

• A. The username and password are incorrect.
• B. The server has an incorrect date configured.
• C. The client is using the wrong type of browser.
• D. The wrong authentication mechanism is being used.

Correct answer: D

Explanation

The correct answer is D because the server is expecting NTLM authentication, while the client is attempting to use Basic authentication. This mismatch leads to the 401 Unauthorized response. Other options are incorrect as the credentials might be valid, the server's date is not usually a cause for a 401 error, and the client can use curl as it's a valid tool for HTTP requests.