Section 3.95.1. Hostname, SecretKey and IntegrationKey
Section 3.95.2. DefaultFactor(1177 / 1718)
Section 3.95.3. PreAuth
3.95.2. DefaultFactor
If the user does not specify a valid password or factor, this
will be the factor requested from Duo. May be one of "push", "sms",
"phone", "auto". Defaults to "auto".