Works for me. You can also remove one pair of parentheses: 
#!/usr/bin/perl
use warnings;
use strict;

use Test::More;

my $regex1 = qr/(2[0-4]|1?[0-9])?[0-9]/;
my $regex2 = qr/(2[0-4]|1?[0-9])?[0-9]|25[0-5]/;
for my $n (0 .. 1000) {
    if ($n < 250 || $n > 255) {
        is($n =~ /^$regex1$/, $n =~ /^$regex2$/, "match for $n");
    } else {
        ok($n =~ /^$regex2$/, "match 2nd regex for $n");
        isnt($n =~ /^$regex1$/, $n =~ /^$regex2$/, "match for $n");
    }
}
done_testing();

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لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ

In reply to Re: Is this a bug in perl regex engine or in my brain? by choroba
in thread Is this a bug in perl regex engine or in my brain? by nikmit

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