Domain Name System(DNS)

A server that translates web addresses or URLs

What is DNS ?

The domain name system (DNS) is a naming database in which internet domain names are located and translated into Internet Protocol (IP) addresses. The domain name system maps the name people use to locate a website to the IP address that a computer uses to locate that website.Once the DNS server finds the correct IP address, browsers take the address and use it to send data to content delivery network (CDN) edge servers or origin servers. Once this is done, the information on the website can be accessed by the user. The DNS server starts the process by finding the corresponding IP address for a website’s uniform resource locator (URL).

How does it work ???

DNS servers convert URLs and domain names into IP addresses that computers can understand and use. They translate what a user types into a browser into something the machine can use to find a webpage. This process of translation and lookup is called DNS resolution.

1. DNS recursor: The DNS recursor, which is also referred to as a DNS resolver, receives the query from the DNS client. Then it communicates with other DNS servers to find the right IP address. After the resolver retrieves the request from the client, the resolver acts like a client itself. As it does this, it makes queries that get sent to the other three DNS servers: root nameservers, top-level domain (TLD) nameservers, and authoritative nameservers.
2. Root nameservers: The root nameserver is designated for the internet’s DNS root zone. Its job is to answer requests sent to it for records in the root zone. It answers requests by sending back a list of the authoritative nameservers that go with the correct TLD.
3. TLD nameservers: A TLD nameserver keeps the IP address of the second-level domain contained within the TLD name. It then releases the website’s IP address and sends the query to the domain’s nameserver.
4. Authoritative nameservers: An authoritative nameserver is what gives you the real answer to your DNS query. There are two types of authoritative nameservers: a master server or primary nameserver and a slave server or secondary nameserver. The master server keeps the original copies of the zone records, while the slave server is an exact copy of the master server. It shares the DNS server load and acts as a backup if the master server fails.

How to perform DNS lookup

Type nslookup followed by the IP address and press ‘Enter. ‘ For example, it can be nslookup 8.8. 8.8. Now, the command prompt will return the DNS name and the IP you entered. in the cmd or terminal.

On a Windows computer you can find your DNS by going to the command prompt, typing “ipconfig/all”, and then hitting Enter.

Type nslookup followed by the IP address and press ‘Enter. ‘ For example, it can be nslookup 8.8. 8.8. Now, the command prompt will return the DNS name and the IP you entered.

Types of DNS servers

DNS Resolver : A DNS resolver (recursive resolver), is designed to receive DNS queries, which include a human-readable hostname such as “www.example.com”, and is responsible for tracking the IP address for that hostname.

DNS Root Server : The root server is the first step in the journey from hostname to IP address. The DNS Root Server extracts the Top Level Domain (TLD) from the user’s query — for example, www.google.com provides details for the .com TLD Name Server. In turn, that server will provide details for domains with the .com DNS zone, including “example.com”.

Authoritative DNS Server : Higher level servers in the DNS hierarchy define which DNS server is the “authoritative” name server for a specific hostname, meaning that it holds the up-to-date information for that hostname.The Authoritative Name Server is the last stop in the name server query — it takes the hostname and returns the correct IP address to the DNS Resolver (or if it cannot find the domain, returns the message NXDOMAIN).