I have two websites and one dedicated server for them.multiple times I asked privious server manger why he offered me to use ns1.dnsexit.com and ns2.dnsexit.com .I told him we can have and use our own child name servers why we don`t use tham.he said there is not problem. now I changed my manager ,created my own nameservers with our ip numbers.I want to know why he used the dns`s.were they making any bad influences on performace of my websites or my server?
He may be comfortable using the 3rd party name servers as it saves your time to install and manage bind service on your server. Having your own name servers pointing to your servers gives you an advantage as you can manage the DNS zone file yourself.
Yes, madaboutlinux might have told the exact cause. Your server manager might have used your server provider's nameservers in-order to rectify the overburden to install and configure Bind in your server. Using custom nameservers also has the benefit of convincing your customers.
You'll be better off just making your own nameservers, and having them point to the other ones. That way you don't have to set up bind, but you can still use ns1.yoursite.com etc