The very oldest rfcs say you should have your nameservers in different places, both netwise and geographically, so that no one event will bring them all down.
Some people say this isn't important because if your dns is down the servers probably are too, but this isn't completely true. The exception is email.
If your server or network goes missing temporarily, taking all your nameservers with it, then anyone who tries to send mail to one of your customers will get an immediate and confusing failure message.
Then they phone the person they are trying to email and that person phones you.
If however your server disappears momentarily, but you still have a functioning nameserver in another location, the email will be accepted from the sender and queued on their outbound mailserver until the message can be delivered (or until the retry time-out expires).
In my opinion that's a better thing to have happen. You don't want people phoning you every time there is a net burp or you have to reboot your server.
So despite what practically every cpanel "host" says, there is benefit to having nameservers in different places.