Many web servers are configured not to resolve the IP addresses of clients connecting (Apache for example, is configured this way by default) simply because most people don't ever use that information, and doing a DNS request for every connection to your web server to get information you aren't going to use anyway is somewhat wasteful. In this situation, the best thing for you to do is to get $REMOTE_ADDR instead, and resolve it yourself if you really need a hostname instead of an IP address.
| We're not surrounded, we're in a target-rich environment! |
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