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Starting in NIOS version 7.1.0, there is a global export feature which would make this pretty easy to do. On any screen in your Grid Manager GUI where you see the CSV Job Manager button in the side toolbar, click on that and if your version of NIOS supports it, you will see a CSV Export tab.

From there, click on the New CSV Export Job button (a round sun like shape) to open the Global CSV Export Wizard. Here, uncheck the All Objects check box, enable the check box for IPv4 DHCP Ranges and then click on the Export Data button.

Follow the prompts to complete the export and once done, you'll have a nifty spreadsheet that you can sort and filter to get the data that you're looking for here. Any ranges assigned to a failover association will have the association name listed in the failover_association column. This will be blank otherwise.

Hope this helps!