What is Domain Server (DNS)?
Last updated on May 29th, 2023 at 10:42 am
A Domain Name System (DNS) is a system that translates domain names into IP addresses. It acts as a directory for the internet, allowing users to access websites using human-readable domain names instead of complex IP addresses. When a user enters a domain name in their browser, the DNS server is responsible for resolving the domain name to the corresponding IP address, enabling the user to access the desired website. DNS also handles other functions like email routing and domain name registration.
How Does DNS work?
DNS works by translating human-readable domain names into IP addresses that computers can understand. When a user enters a domain name in their browser, their device sends a DNS query to a DNS resolver or server. The resolver then checks its local cache for the corresponding IP address. If the information is not available, the resolver contacts other DNS servers in a hierarchical manner until it finds the IP address associated with the domain name. Once the IP address is obtained, the resolver sends it back to the user’s device, allowing them to connect to the desired website or service on the internet.
There are 4 DNS servers involved in loading a webpage
When loading a webpage, typically four DNS servers are involved in the process:
Recursive DNS Resolver
This is the DNS server configured on the user’s device or network. It receives the initial DNS query from the user’s browser and begins the process of resolving the domain name.
Root DNS Server
The recursive resolver sends a query to the root DNS server, which is the starting point of the DNS hierarchy. The root server responds with a referral to the appropriate Top-Level Domain (TLD) server.
TLD DNS Server
The recursive resolver then contacts the TLD DNS server responsible for the specific domain extension (.com, .org, etc.). The TLD server provides the resolver with the authoritative DNS server responsible for the requested domain.
Authoritative DNS Server
Finally, the recursive resolver queries the authoritative DNS server identified by the TLD server. The authoritative server provides the IP address associated with the domain name, which is then passed back to the user’s device, allowing the webpage to load.
What’s the difference between an authoritative DNS server and a recursive DNS resolver?
The main difference between an authoritative DNS server and a recursive DNS resolver lies in their roles and functions within the DNS infrastructure.
An authoritative DNS server is responsible for storing and providing the actual DNS records for a specific domain. It holds the authoritative information about the IP addresses associated with the domain names it manages. When queried, it responds with the accurate and up-to-date information for the requested domain.
On the other hand, a recursive DNS resolver is a DNS server that receives DNS queries from clients and takes on the task of resolving those queries. It performs the necessary steps to find the IP address associated with a domain name by querying other DNS servers in a hierarchical manner until it obtains the authoritative response. The recursive resolver acts as an intermediary between the client and the authoritative DNS server, handling the resolution process on behalf of the client.
A DNS lookup involves multiple steps to translate a domain name into its corresponding IP address. The process typically includes the following steps:
- The client sends a DNS query to the local DNS resolver.
- The resolver checks its cache for the requested domain’s IP address.
- If not found, the resolver queries the root DNS servers for the top-level domain’s authoritative DNS server.
- The resolver then contacts the authoritative DNS server to retrieve the IP address.
- The authoritative server responds with the IP address, which is sent back to the resolver.
- The resolver caches the IP address and returns it to the client, enabling the connection with the desired website or service.
What is a DNS resolver?
A DNS resolver, also known as a recursive resolver, is a key component of the DNS infrastructure. It is a server or software that receives DNS queries from clients and performs the task of resolving those queries. The resolver is responsible for navigating the DNS hierarchy, contacting various DNS servers, and retrieving the accurate IP address associated with a domain name. It acts as an intermediary between the client and authoritative DNS servers, handling the resolution process and providing the client with the final IP address needed to establish a connection with the desired resource on the internet.
What are the types of DNS Queries?
The types of DNS queries include A (Address), AAAA (IPv6 Address), MX (Mail Exchanger), CNAME (Canonical Name), NS (Name Server), TXT (Text), and SRV (Service) queries. Each query type serves a specific purpose in retrieving different types of information from DNS servers.
The three types of DNS queries are:
This query is made by a DNS resolver to request information from other DNS servers on behalf of the client. It recursively follows the DNS hierarchy to obtain the final response.
This query is made by a DNS server to request information from another DNS server. Unlike recursive queries, iterative queries do not follow the entire hierarchy and instead receive a referral response from the queried server.
Reverse DNS Query (PTR):
This query is used to retrieve the domain name associated with a given IP address. It is the opposite of a typical DNS lookup, where the IP address is resolved to a domain name.