Issue Websites are not showing up

[Alex95]

I've installed Plesk on a VPS, added a new domain, and changed the custom name servers and personal dns name servers for my domain on namecheap.com.

Using mxtoolbox.com's dns lookup I get the error:
Loop detected! We were referred back to 'XXX.XX.XXX.XXX'

Using mxtoolbox.com's whois lookup I get:

Name Server NS1.XXXXXXX.COM
Name Server NS2.XXXXXXX.COM