$ cat 910595.pl
#!/usr/bin/perl
use strict;
use warnings;
use Net::IP;

my @IPranges = map { new Net::IP($_) } <DATA>;

@IPranges = sort {
              # We want largest range first
              ($b->size() <=> $a->size())
              # use IP as next key
              || ($a->ip() cmp $b->ip())
            } @IPranges;

print join("\n", @IPranges), "\n";
__DATA__
1.2.3.0/24
1.2.0.0/16
192.168.0.0/16
192.168.4.0/24
192.168.4.192/26
127.0.0.1/32
10.0.0.0/8

$ ./910595.pl
10/8
1.2/16
192.168/16
1.2.3/24
192.168.4/24
192.168.4.192/26
127.0.0.1/32