The -setdefault option was used to set a certificate as the default certificate in a Key Database file, but this feature no longer works and is deprecated.

Instead, you will use the SSLServerCert directive in your httpd.conf file to specify the server certificate to use.

LoadModule ibm_ssl_module modules/mod_ibm_ssl.so
Listen 443
<VirtualHost *:443>
  SSLEnable
  SSLServerCert *.example.com
</VirtualHost>
KeyFile "/path/to/example.kdb"
SSLStashFile "/path/to/example.sth"
SSLDisable