The Domain Name System (DNS) is a hierarchical decentralized naming system for computers, services, or other resources connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities. Most prominently, it translates more readily memorized domain names to the numerical IP addresses needed for locating and identifying computer services and devices with the underlying network protocols.
In Internet world, there are two type of DNS Search mechanisam available 1) Recursive 2) Iterative. Below picture will explain these search types.
Recusive DNS Search:
Iterative DNS Search:
What is IPv4 and IPv6?
Top Level Domains
IANA (Internet Assigned Numbers Authority)
Domain Registrars
WhoIS DB for Domain Name search
InterNIC Service of ICANN
Below is simple Example of how browser resolving domain name to IP Address
Below is simple Example of how Hosting server change happens in Domain Registrar site
Hosted Zone
A hosted zone is a collection of resource record sets for a specified domain. You create a hosted zone for a domain (such as example.com), and then you create resource record sets to tell the Domain Name System how you want traffic to be routed for that domain. When you create a hosted zone, Amazon Route 53 automatically creates a name server (NS) record and a start of authority (SOA) record for the zone. The NS record identifies the four name servers that you give to your registrar or your DNS service so that DNS queries are routed to Amazon Route 53 name servers.
DNS Record Types
SOA (Start Of Authority) Record:
SOA means Start of Authority and is a significant part of a zone file in the domain name system (DNS). A SOA-Record contains important management information about the zone, especially regarding the zone transfer. Keeping SOA record in DSN server is standard, this will help at the time Zone file Change/Transfer happens from Primary to Secondary servers.
Background:
Normally DNS name servers are set up in clusters. The database within this clusters is synchronized through zone transfers. The SOA-Record in the zone file contains data to control the zone transfer. This is the serial number and different timespans.It also contains the e-mail-address of the responsible person for this zone as well as the name of the primary master server. Usually the SOA-Record is located at the top of the zone. A zone without a SOA-Record does not meet the standard and is therefore not transferable.
- Identify the DNS server that is authoritative for all information within the domain.
- List the email address of the person in charge of the domain.
- Control how often secondary servers check for changes to the zone file.
- Control how long secondary servers keep the zone file active when the primary server cannot be contacted.
- Control how long a negative response is cached by a DNS resolver (but for some DNS servers, this is also how long a DNS resolver should cache any response).
Note: Name Server is nothing but one of the Physical Domain Name Server of AWS’ Route 53 service. This domain name server (DNS) Server contains all the records which are being used to resolve Internet address Name to Internet IP when user request for web site via Browser.
TTL (Time to Live) Record:
CNames (Canonical Names) Record:
Alias Record:
Below are few other DNS records in industry.
Simple Routing Policy
When you create a resource record set, you choose a routing policy, which determines how Amazon Route 53 responds to queries. Below are Routing policies available in AWS.
- Simple routing policy – Use for a single resource that performs a given function for your domain, for example, a web server that serves content for the example.com website.
- Failover routing policy – Use when you want to configure active-passive failover.
- Geoproximity routing policy – Use when you want to route traffic based on the location of your resources and, optionally, shift traffic from one resources in one location to resources in another.
- Latency routing policy – Use when you have resources in multiple locations and you want to route traffic to the resource that provides the best latency.
- Multivalue answer routing policy – Use when you want Amazon Route 53 to respond to DNS queries with up to eight healthy records selected at random.
- Weighted routing policy – Use to route traffic to multiple resources in proportions that you specify.
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