From the Tenable blog post:
Nessus recently added capabilities to perform configuration and compliance audits in two major areas of the enterprise. First, Tenable added the ability to audit enterprise Cisco networking equipment, namely Cisco’s Nexus NX-OS. Then, we expanded and greatly enhanced support for auditing VMware vSphere and vCenter. Now, we’ve added support for auditing NetApp Data ONTAP storage devices. The new .audit is primarily based off the NetApp hardening guides (technical reports TR-3649 and TR-3996).