I don't think you can easily block a TLD because it can take a long time for your server to look up a host name... and it may not be able to find one for an IP at all.
Best bet is to monitor your logs and find the range of offending IPs. Most web servers (and certainly all firewalls if you're running one) will let you screen by IP range including wildcards.
Even the small footprint BadBlue server (link below) will let you do this. Check out the doc for your server on restricting IPs... that's your best bet AFAIK.
Dave
Pretty cool... and thanks for the link to code examples. One suggestion - reduce font size so that users don't have to scroll as much. I really like small fonts (like on CNet's or Microsoft's sites for instance where everything is compact). Good job.
Dave
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