Silk Central LDAP integration supports plain-text authentication and SSL authentication. 

Your directory service must either allow anonymous queries or a user with read rights on the directory must be provided.

This means that within the BindDN field, it is optional only if you use "Anonymous Queries".
If not, you must have a user account with read rights, that preferably has a permanent password.
If the password of the BindDN account changes, the verification will no longer be valid.

To setup an LDAP Server:

1. In the menu, click Administration > System Settings.
2. Click the LDAP Servers tab.
3. Click New LDAP Server. The New LDAP Server dialog box appears
4. Type a Name for the server and optionally a Description.
5. Check the Active check box to activate the server for use with Silk Central.
6. Type the Hostname or IP-address of the LDAP server and the Port used for the LDAP service.
7. Check the Use SSL check box to connect to the server through SSL.
8. In the Bind DN field, type the domain name of the user who is to be used to bind to the LDAP service.
9. Type the Password of the user defined by Bind DN.
10. Type the Base DN root for LDAP queries and the Filter that is to be used for querying LDAP.
11. Click Test to perform a test connection to the LDAP server.
12. Click OK to save your settings.

Further help can be found at the following help video.

The tool below can be used to return LDAP information.

ldapReturnLDAPInfo.zip