What is Hosted Zone : A container for DNS records related to a specific domain and its subdomains. Wherever configuration related to domain should be done here. 

NS Record:  Authorized name server record (This should know where request should goes). As eg. As AWS / Hostinger / GoDaddy giving us 2-3 name server records. 

SOA:  Start of authority, used to designate the primary name server and administrator responsible for a zones.

Record Type :

• A : Route a traffic to an ipv4 address. here TTL use for cost optimization via reducing TTL time in min, hr. day.
• AAAA : Route a traffic to an ipv6 address (128 bits).
• CNAME: Route traffic to another domain  name. To understand when we create LB in AWS we can’t get ip address it’s give us dns url , when we create S3 static website AWS we can’t get ip address it’s give us bucket url , also in cloud front service as well. Use only for sub-domain.
• MX: Specific mail servers ip address.
• TXT : It include Information that helps external network servers and services handle outgoing email from your domain. e.g Check via nslookup -type=TXT me.dev-ops.tech. Real life use case in our OTP in messages to verify identity. Another in lemon language — Verify domain belongs to this persion via TXT record.
• Alias: Alias use for root domain as ell sub-domain. (eg. me.dev-ops.tech). Alias are free to use in cloud. 
• MX : Specifies mail server.
• PTR : It is just reverse A record. Convert domain name to ip address.

Health Check in Route53 :  Monitor health check of endpoint