AWS Domain Name System
AWS Domain Name System
Domain Name System Concepts:
DNS is a globally distributed service uses a hierarchical name structure which are separated by dot (.). DNS is divided in to Top –Level Domain (TLD), Second –Level Domain (SLD) and many lower levels domain below SLD.
Example: www.dclessons.com and www.racks .dclessons.com, in both the TLD is (.COM) and dclessons is SLD.
Amazon provides the DNS services via Amazon Route 53 which is authoritative DNS system of Amazon. It works same as another DNS service like answers DNS queries, Translate the domain names to IP address, CNAME , A Record , Etc.
TLD is the most general part and is present farthest portion to the right, some example are .com, .net, .org, .gov, .edu etc.
ICANN (Internet Corporation for Assigned names and Numbers) has given management control to certain parties, which then distribute domain names under TLD. These Domains names are then registered with Inter NIC (Network Information Center) which ensures the uniqueness of the domain names across internet. Each domain name which is registered, then further registered in a central database called WholS database.
A domain name is a URL which provides a certain name for certain purpose and is uniquely available over internet.
Example: dclessons.com, is a domain name which is for certain purpose and is uniquely available over internet.
Host defines individual host, services, and any resources in domain name, which are accessible through a domain.
Example: if any certain API is to be accessible via internet under domain name, then we can provide the URL like: api.dclessons.com or any SFTP services then stfp.dclessons.com. So api or SFTP just represents a host, Services.
As we know that DNS work in hierarchal manner and allow large domains to be extended to multiple sub domains. A TLD can have multiple sub domains under them like dclessons is the sub domain under (.com) TLD.
Each SLD can also have sub domains under it, example www.racks .dclessons.com, here racks is the sub domain under SLD.
The difference between host and sub domains is that, host represents any computer, services, or resources but subdomain extend parent SLD, which is sub dividing domain itself.
Fully Qualified Domain Name (FQDN):
It is the absolute domain name and ends with dot( .) like www.dclessons.com. Which indicates root of the DNS hierarchy.
Example: Explained in below figure: DNS 9-1
It is just like DNS or we can say that Name server is Computer designated name server which translate domain names to IP address. These name servers works like DNS and has capability to re direct the DNS request from itself to another name server, they can only answer the queries about domain s which they control.
It is the simple text file that contains the mapping between domain names and IP address. It resides in the name servers and defines the resources under specific domain.
Top level Domain (TLD) Name Registers: It is an organization that manages and reserves the Internet domain names. A domain name registrar must be accredited by a generic TLD, and/ or Country code TLD.
Top Level Domain name Servers:
After root servers returns IP address of the server responsible for TLD of a request , the requestor send the new request to that address and which further sends request to name server responsible for that domain to locate that domain ID.
Domain Level Name Servers:
Now if the requestor has IP address of the name server that is responsible for proving the actual IP address of that domain ex dclessons.com, the requestor will send the new request to name server asking about IP address of that Domain name ex dclessons.com .
Name server check the zone file and find the IP address associated or mapped to dclessons.com. and thus provides to requestor.