$(document).ready(function()
{
    spans = $("span.rdns_lookup");
    spans.append(' <a><img src="design/rdns-lookup.gif"></a>')
    spans.each(function()
    {
        link = $(this).find("a")
            .css('cursor', 'hand')
            .attr('rel', $(this).attr('rel'));
            
        link.click(function(e)
        {
            $(this).find('img').attr('src', 'design/rdns-lookup2.gif');
            $.getJSON(
                './ajax.py', 
                { 'request': 'rdns', 'ip': $(this).attr('rel') }, 
                function(data)
            {
                selector = 'span[class=rdns_lookup][rel=' + data.ip + ']';
                $(selector).text(data.rdns);
            });
        });
    });
});