Pepwave Mini with x509 certificate

Hi ,
I would like to know IPsec VPN with Certificate. I can configure VPN with certificate and VPN is up and traffic is passthrough ipsec tunnel .i only want to know the authentication flow.
I use remote IP address and then i also check Local ID and remote ID box to use DN or FQDN like below picture. I would like to know if i configure like that authentication will use remote IP address or local ID or remote ID ? or Do i need to type DN or FQDN in the box manually ? or Pep will find DN or FQDN name in certificate itself automatically ?