in reply to Reliable FQDN from IP
Using 5.8.8 and due to tight control of our software stacks I cannot make use of non-core Perl modules.
Yes, even you can use CPAN. On one hand, the poor woman who has to fill out our due-diligence reports for our lawyers hates the work. On the other hand, she knows that this is why I'm so productive. So we go through the extra overhead. Before I joined the team, everyone just thought they had to rely solely on whatever was already on the system. As space_monk suggests, I've pursued a path of expanding it. That's still my suggestion here.
Talk to your manager about this. At your current rate of pay and how long it would take to rewrite the functionality provided by one of the CPAN modules, or at least the subset you need (please take into consideration the extra testing you'll have to perform), what does that cost? And what does it cost to add an extra module (or, in my case, 100 modules)? Generally, it's cheaper to use the CPAN module. And I say that even when I have to involve the lawyers for re-distribution approval.
Please don't take "tight control" to automatically mean "no non-core". Because most people are fairly reasonable about this type of thing - if it makes you more productive, they'll probably be in favour of finding a way to help.