To find out which certificates a Rest data source is using for the SSL handshake:

1.  Set Studio >> Administration >> Configuration >> Server >> Communications >> Generate SSL Diagnostics(On Server Restart) to true, and restart the TDV server for the change to take effect. 

2.  Click the Test Connection button.

3.  An SSL trace will be written to cs_server.out. The trace will tell you the following:

(i)  The name of the truststore file. 
Example
trustStore is: C:\apps\cis704\conf\server\security\cis_server_truststore_strong.jks

(ii)  The certificates that are being used for the handshake. To find the certificates, look for the message "Found trusted certificate".
The example below shows two certificates.
Example
***
Found trusted certificate:
[
[
  Version: V3
  Subject: CN=Cabot CyberTrust Root, OU=CyberTrust, O=Cabot, C=IE

Found trusted certificate:
[
[
  Version: V3
  Subject: CN=DigiCert Global Root CA, OU=www.digicert.com, O=DigiCert Inc, C=US