Im sure some random comment somewhere could help so I'm sorry if you know where that is but I need some help and have read a ton trying to double check my work here... I am new to VPS and didnt know I needed to know so much about DNS lol. Ive been offering managed hosting for like 8 years but new to VPS so anyways...
I have my main domain - domain.space (yes that is the correct extension). I setup my vps with no subdomain as the hostname. Seems like some people suggest doing a subdomain too but for me that would work best. From what I can see this shouldn't cause any problems overall.
I setup custom dns at namecheap with ns1 and ns2 pointing to my 1 IP. I have the NS of that MAIN domain pointing to cloudns premium name servers where I have all records and subdomains routing correctly from what I can see (including A records for ns1 and ns2). IntoDNS confirms that main domain should be setup perfectly.
SO here's the rub. I setup a new customer (lets call them customer.com) with my custom name servers, ns1.domain.space and ns2.domain.space. Godaddy accepted them no problem. BUT even though my ip, and ns1 and ns2 all resolve to my VPS correctly, whatsmydns.com only shows customer.com cached in turkey!! And into dns says my IP doesnt resolve at all?!?! Its been about 2 days. What in the world?!
FYI - I do have necessary A and NS zone records setup with customer.com's zone file within their VPS. Also I have another customer correctly setup on a separate account on that VPS but not by using ns1 and ns2 as NS.