There really isn't any need for that socket stuff.

use URI;
my $url = 'http://foo.bar.com';
my $uri = new URI($url);

if( $uri->host =~ /[a-zA-Z\-]/ ) { # or /[^\d\.]/
#    it's an IP dag-nabbit
}
[download]

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** The Third rule of perl club is a statement of fact: pod is sexy.