In AWS, for Route 53, when you register a new domain (like kkhosravi.com), and the corresponding Hosted Zone with the same name is created (that contains all the A records, CNAME records, etc for routing traffic for your domain and subdomains), two records are created automatically: the [...] records and the SOA record.

NS

^^ the NS record identifies the name servers for the hosted zone (e.g. samsungknox.com NS ns-650.awsdns-17.net 172800TTL). Note if you switch DNS service away from Route53 to another service, the TTL becomes a factor and it could take 172800 seconds (48 hours) for the changes to propegate across the internet.
^^^ the SOA (Start of Authority) record provides information about a domain and the corresponding Amazon Route 53 hosted zone. (e.g. samsungknox.com SOA ns-650.awsdns-17.net awsdns0hostmaster.amazon.com 1 7200 900 1209600 86400
^^^^ You do not need to ever edit these as they are created automatically when you register your domain with Route53 (or are imported if you say use godaddy.com for the domain name registration)