any chance you're hitting the SIDN WHOIS lookup limits? I know the default whoisserver file uses the port43 address, so likely has a whois limit of 15 per day; the website has a 500 lookup limit - so i'm not sure if/what the limit would be via API?   the following may not help you directly, but a fellow Dutch WHMCS user told me that he uses...   .nl|http://whois.domain-registry.nl/is?domain=|HTTPREQUEST-is free as it gives more consistent results that the default WHOIS (returns availa