ISPs and reverse DNS lookups
Solution 1:
It depends on the provider and its policies. Normally, you will not delegated reverse DNS authority without you having some large block of continuous IP space. If it's just normally one to eight IPs, you won't get control over it. In that case the ISP will handle reverse DNS.
In most hosting situations you must send in a support ticket to contact the ISP/Upstream/Datacenter/Etc to update the PTR record. But, some providers, like Softlayer, allow you modify it yourself via a control panel.