Private Agent can monitor web sites which require SSL certificate for authentication. A client certificate is a type of digital certificate that is used by client systems to make authenticated requests to a remote server.  The process of agent install is completely the same, you simply need to export the certificate to Private Agent and specify its name in the corresponding monitoring task. See the full guideline below.

1. First, install an SSL PFX certificate into your system. Make sure you marked the private key as exportable. The certificate can be installed on any machine in your network − not necessary to do it on the machine with Private Agent installed. 

2. Run Certificate Manager and find the certificate you have installed. 

3. Right-click the certificate, point to All Tasks and then select Export.

4. Follow the steps in Certificate export Wizard: click Next -> Yes, export private key -> Next -> Export all extended properties -> Next -> in the Password field, enter C6837385-35FA-4051-AF66-0F974BBC6FE6 -> Next-> enter a file name (e.g., cert.pfx) -> Next -> Finish.

6. Copy the resulting file to Private Agent folder C:\ProgramData\Dotcom-Monitor\Private Agent\Certificates.

7. Restart Private Agent service.

Optionally, if you have already had several certificates for the same domain installed on Dotcom-Monitor you can force a particular certificate to be used by Private Agent. To accomplish it, specify it’s file name in task configuration ( the Task tab > the SSL/ Certificate Check section > the Client Certificate field).