Bulk Reverse DNS query with DIG

I want to do a bulk reverse DNS query to a specific nameserver. Currently, after searching here and Google. I got it to work for 1 entry at the time with the following command: dig @NAMESERVER -x 10.10.10.10 +short This returns exactly what I want. But If I want to do this for multiple IP addresses, it fails. What I did was to make a list of 2 IP addresses to test. I'm trying to use the following command: dig @NAMESERVER -x -f dnsquery.txt +short This does not show any result, what am I doing wrong? The input files has 2 lines, each with 1 IP address: 10.10.10.10 10.10.10.11