WHMCS and DAS
WHMCS uses the whois in order to perform domain name availability checks. See http://docs.whmcs.com/Domains_Configuration#Adding_Additional_WHOIS_Services
The search is fast
The search is not reliable due to the fact that:
- A deleted domain name in redemption or quarantine status are sometimes no longer displayed into the whois whereas it is still unavailable
- Registry reserved/blocked domain names are sometimes not displayed into the whois
- Some countries doesn't provide a whois or respond very slowly
- Some countries have implemented rate limiting per minute, per hour or per day.
- The domain name syntax is often not managed by the whois server.
In addition, the whois doesn't make any difference between a regular domain name and a premium one
NETIM provides a Domain Availability Service over HTTP especially for WHMCS.
Edit the file /includes/whoisservers.php Replace the line corresponding to .extension by .extension|https://www.netim.com/bin/das-whmcs.php?login=XXXX&password=YYYY&domain=|HTTPREQUEST-: AVAILABLE Replace ".extension" by the one you want to resell Replace "XXXX" by your reseller ID Replace "YYYY" by your special password to be asked to our support team (this is not your reseller password for security reasons)
Do the same for all third level domain names under the extension, if any.
Make a test:
Premium domain names
As WHMCS doesn't manage premium domain names, our DAS will return a not available result preventing you to sell them without the capacity to honor the order