public String getCertificateMode() {
        return this.certificateMode;
    }
<p>
The mode of the certificate.
</p>
<p>
<code>DEFAULT</code>: A certificate in <code>DEFAULT</code> mode is either generated by Amazon Web Services IoT
Core or registered with an issuer certificate authority (CA) in <code>DEFAULT</code> mode. Devices with
certificates in <code>DEFAULT</code> mode aren't required to send the Server Name Indication (SNI) extension when
connecting to Amazon Web Services IoT Core. However, to use features such as custom domains and VPC endpoints, we
recommend that you use the SNI extension when connecting to Amazon Web Services IoT Core.
</p>
<p>
<code>SNI_ONLY</code>: A certificate in <code>SNI_ONLY</code> mode is registered without an issuer CA. Devices
with certificates in <code>SNI_ONLY</code> mode must send the SNI extension when connecting to Amazon Web
Services IoT Core.
</p>

@return The mode of the certificate.</p>
        <p>
        <code>DEFAULT</code>: A certificate in <code>DEFAULT</code> mode is either generated by Amazon Web
        Services IoT Core or registered with an issuer certificate authority (CA) in <code>DEFAULT</code> mode.
        Devices with certificates in <code>DEFAULT</code> mode aren't required to send the Server Name Indication
        (SNI) extension when connecting to Amazon Web Services IoT Core. However, to use features such as custom
        domains and VPC endpoints, we recommend that you use the SNI extension when connecting to Amazon Web
        Services IoT Core.
        </p>
        <p>
        <code>SNI_ONLY</code>: A certificate in <code>SNI_ONLY</code> mode is registered without an issuer CA.
        Devices with certificates in <code>SNI_ONLY</code> mode must send the SNI extension when connecting to
        Amazon Web Services IoT Core.
@see CertificateMode
aws-java-sdk-iot/src/main/java/com/amazonaws/services/iot/model/Certificate.java