The NS, or Name Server records of a domain, reveal which servers handle the Domain Name System (DNS) records for it. Setting the name servers of a given hosting provider for your domain name is the most convenient way to forward it to their system and all its sub-records will be handled on their end. This includes A (the IP address of the server/website), MX (mail server), TXT (free text), SRV (services), CNAME (forwarding), etc, if you want to change any of these records, you'll be able to do it by using their system. To put it differently, the NS records of a domain address show the DNS servers which are authoritative for it, so when you attempt to open a web address, the DNS servers are contacted to retrieve the DNS records of the Internet domain you want to reach. In this way the site that you'll see is going to be retrieved from the proper location. The name servers typically have a prefix “ns” or “dns” and each and every domain has at least 2 NS records. There isn't any sensible difference between the two prefixes, so what type a host company is going to use depends entirely on their preference.