A direct revert from ONTAP 9.7 to ONTAP 9.5 using the standard system node revert-to command is not a supported path. The standard revert procedure is typically limited to the immediately preceding release (e.g., from 9.7 to 9.6). When a direct revert is not supported, the correct procedure is to perform a non-disruptive downgrade. This process involves using netboot to boot each node from a TFTP server that hosts the target ONTAP software image (9.5 in this case). This effectively performs a clean installation of the older software version while preserving the existing data and configuration.

B. The "boot backup procedure" (using system node revert-to) is not supported for reverting from ONTAP 9.7 directly to 9.5. This path skips a major release (9.6).

C. A direct revert from ONTAP 9.7 to 9.5 is not a supported operation. The supported revert path from 9.7 is to ONTAP 9.6.

D. This option is illogical. It suggests reverting to an invalid version (ONTAP 8.6) and then moving between versions in a nonsensical order.

1. NetApp ONTAP 9.7 Upgrade and Revert/Downgrade Guide, Page 41, Section: "Reverting or downgrading ONTAP".

This section distinguishes between reverting and downgrading. It states, "Reverting is the process of returning to a previous ONTAP release by using the backup ONTAP image... Downgrading is the process of installing a previous ONTAP image on the boot device." This clarifies that different procedures exist.

2. NetApp ONTAP 9.7 Upgrade and Revert/Downgrade Guide, Page 42, Table 10: "Supported revert paths for ONTAP 9.7".

This table explicitly shows that from ONTAP 9.7, the only supported revert target is ONTAP 9.6. ONTAP 9.5 is not listed, confirming that a direct revert is not allowed.

3. NetApp ONTAP 9.7 Upgrade and Revert/Downgrade Guide, Page 46, Section: "Downgrading ONTAP nondisruptively".

This section details the procedure for when a revert is not possible. Step 4 of the workflow states: "Boot the node from the TFTP server to download the target ONTAP software image... The netboot command is used for this purpose." This confirms that netboot is the correct procedure for a downgrade.