ldns-compare-zones --version (return code: 0)
ldns-compare-zones: invalid option -- '-'
ldns-compare-zones version 1.6.17 (ldns version 1.6.17)
ldns-compare-zones --help (return code: 0)
ldns-compare-zones: invalid option -- '-'
Usage: ldns-compare-zones [-v] [-i] [-d] [-c] [-s] <zonefile1> <zonefile2>
-i - print inserted
-d - print deleted
-c - print changed
-a - print all differences (-i -d -c)
-s - do not exclude SOA record from comparison
-z - do not sort zones
-h - show usage and exit
-v - show the version and exit