If you want your customers to be able to check the availability of new domains, you will need to add the appropriate Whois servers.
The example steps below add a Whois server for .aarp.
Add Domain Availability Checks
To add a new Whois server to WHMCS:
1. Find the Whois server for the desired TLD. In most cases, you can find this in the IANA root database.

2. Run the following command on your server:
telnet whois.nic.aarp whois
3. Enter any available domain using that TLD (for example, example-domain-check.aarp) The output will show the Whois server's match string (in this example, No match for):
No match for "EXAMPLE-DOMAIN-CHECK.AARP".
5. Create a /resources/domains/whois.json file on your server.
6. Add the TLD extension, the Whois server address, and the match string to the file using the following format:
[
{ "extensions": ".aarp",
"uri": "socket://whois.nic.aarp",
"available": "No match for"
}
]
7. Save the file.
The End! should you have any inquiries, we encourage you to reach out to the Vercaa Support Center without hesitation.