The documentation needs prerequisites (perhaps in the introduction) which spell out that a knowledgeable understanding of X.509 (and PKI / PMI systems in general) is required before attempting to configure X.509 Auth or SSL with MongoDB.

We get customers expecting a How-To on setting up such things as a CA (Certificate Authority) which appears to be a reasonable expectation without a background in PKI/PMI systems.

MongoDB is not a CA, nor can we provide the appropriate support for customers wanting to set up their own internal CA - this is outside the scope of MongoDB support.

It would be useful to say what is required knowledge before attempting to set-up auth or crypto. I suggest a "prerequisites" link at the top of such tutorials that require knowledge of systems outside the scope of MongoDB, for example:
http://docs.mongodb.org/manual/tutorial/configure-ssl/
http://docs.mongodb.org/manual/tutorial/configure-x509/