Hi Atif,
Please refer
If you are using a domain account for scanning SQL Server databases, the syntax of “<domain>\<username>” in the credentials field of the scan will not work. This syntax will cause a login error on the scan.
In order to specify the domain, it must be included in the database connection string using the following syntax:
SQLSERVER://<server>:<port>/<database>;domain=<domain>
In the scan credentials field, you then must specify the domain user name without the domain qualification.
More information on the exact syntax of the database call through the JTDS driver can be found at:
http://jtds.sourceforge.net/faq.html#instanceName