Recently (10 March 2020), Windows rolled out a security update that offers protection for applications against man-in-the-middle attacks. With this update you can now configure LDAP Channel binding and LDAP signing for Active Directory servers. We highly recommend you perform the LDAP Channel binding and LDAP signing as it will prevent man-in-the-middle attacks in environments that have enabled Active Directory import in ServiceDesk Plus.
Refer the link below for more information on this
https://support.microsoft.com/en-in/help/4520412/2020-ldap-channel-binding-and-ldap-signing-requirements-for-windows
Refer the links given below to know how to configure LDAP Channel binding and LDAP signing