Hello,
in docs for 4.2 RHV (I think it applies to oVirt 4.2 too) for attaching to AD there is the statement
"
To set up secure connection between the LDAP server and the Manager, ensure a PEM-
encoded CA certificate has been prepared. See Section D.2, “Setting Up Encrypted
Communication between the Manager and an LDAP Server” for more information.
"
and in Appendix
"
To set up encrypted communication between the Red Hat Virtualization Manager and an LDAP server, obtain the root CA certificate of the LDAP server. . .
"
and in readme file referred in the Appendix (/usr/share/doc/ovirt-engine-extension-aaa-ldap-1.3.8/README) there is the command:

"
Active Directory

    Windows: > certutil -ca.cert myrootca.der
    Linux:   $ openssl -in myrootca.der -inform DER -out myrootca.pem
"

In my case on Windows DC (that is a Windows 2012 R2 server with "Domain functional level: Windows Server 2003") I get this error:

C:\Users\Administrator.MYDOMAIN>certutil -ca.cert mydomain.der
CertUtil: The system cannot find the file specified.

C:\Users\Administrator.MYDOMAIN>

What does it mean exactly? 

Thanks in advance,
Gianluca