The Domain Name System (DNS) is a crucial component of the Internet and computer networks. It serves as a decentralized directory for translating human-friendly domain names into machine-readable IP addresses. In this article, we will explore the role, services, and working of DNS in computer networks.
A domain name is a human-readable name – like example.com – that we type in a web browser URL field. The Internet Corporation for Assigned Names and Numbers (ICANN) manages these domain names. Top Level Domain (TLD) refers to the last part of a domain name. For example, the .com in example.com is the Top Level Domain. The most common TLDs include .com, .net, org, and .info. Country code TLDs represent specific geographic locations. For example: .us represents the United States.
Second Level Domain is the part of a domain name that comes right before the TLD – example.com – for example. A subdomain can be created to identify unique content areas of a website. For example, the cluster of cluster.example.com.
The primary role of DNS is to act as a naming system for the Internet and other private networks. It provides a way to associate human-readable domain names with the numerical IP addresses that computers and other networked devices use to identify each other on the internet. Here are the key roles of DNS:
Translation of Domain Names to IP Addresses: DNS resolves domain names to IP addresses, enabling users to access websites, send emails, and connect to various online services by using easy-to-remember names instead of complex numerical addresses.
Load Balancing: DNS can be used to distribute network traffic among multiple servers or data centres, thus improving the reliability and performance of websites and services.
Redundancy and Fault Tolerance: DNS allows network administrators to set up redundant servers and configure failover mechanisms, ensuring that the network remains operational even if some servers become unavailable.
Reverse DNS: DNS also performs the reverse operation, converting IP addresses into domain names. This is useful for tasks like identifying the sender of an email based on the sender’s IP address.
DNS Services
DNS offers several essential services to make the Internet more user-friendly and efficient:
Name Resolution: DNS resolves domain names to IP addresses and vice versa. When you type a URL into your web browser, the DNS system translates that address into an IP address, allowing you to access the requested website.
Caching: To reduce the load on DNS servers and improve response times, DNS systems employ caching mechanisms. These cache stores recently resolved domain names and their corresponding IP addresses, allowing for quicker resolution when a user requests a frequently visited website.
Dynamic Updates: DNS also supports dynamic updates, enabling the automatic updating of DNS records as network configurations change, making it an essential component of modern network management.
Security: DNSSEC (Domain Name System Security Extensions) is a set of security protocols that provide authentication and integrity checks for DNS data, preventing various forms of cyberattacks, including DNS spoofing.
Working of DNS
DNS works in a hierarchical and distributed manner, involving different types of DNS servers, including:
Root Servers: These servers are at the top of the DNS hierarchy and maintain information about top-level domains (TLDs), like .com, .org, and .net. There are only 13 sets of root servers worldwide, and their IP addresses are hard-coded into DNS resolvers.
TLD Servers: These servers handle the next level of the DNS hierarchy, managing domain extensions like .com, .org, or .net. They provide information about the authoritative name servers for specific domains.
Authoritative Name Servers: Each domain has one or more authoritative name servers that contain DNS records for that domain. These servers respond to DNS queries with the IP addresses associated with the domain’s records.
DNS Resolvers: These are the DNS servers that clients, like your computer or smartphone, use to send DNS queries. Resolvers contact root or TLD servers to resolve domain names, and they often cache responses to improve efficiency.
DNS Resolution Process
The DNS resolution process follows these steps:
The client sends a DNS query to the resolver, requesting the IP address associated with a domain name.
The resolver checks its cache for a previously resolved IP address. If found, it returns the result to the client.
If the IP address is not in the cache, the resolver sends a query to the root server, which points it to the appropriate TLD server.
The TLD server then directs the resolver to the authoritative name server for the specific domain.
The authoritative name server provides the IP address, which the resolver caches and returns to the client.
Speed Up DNS Lookups
DNS lookup is a critical component of an application’s performance. As the entry point into an application, the need for reliable and fast DNS lookups is obvious. Importantly, as a user is about to interact with an application, DNS also presents a powerful opportunity to manage the performance of the application by sending users to appropriate service endpoints in today’s distributed environments.
Almost all network connections require an initial DNS lookup, including both machine-to-person (M2P) and machine-to-machine (M2M) communications. Therefore, if a DNS lookup is slow to return a result, for end-users the network will “feel” slow, while for devices it could impact time-critical M2M connections.
Root DNS is 1st level of Hierarchy, and there are 13 Root DNS servers across the globe. It stores the information about various TLD Servers.
Top Level Domain (TLD) servers maintains information about generic domains that ends with .edu, .net, .com, .org, etc and country domains that ends with .us, .uk and .in and etc.
Authoritative DNS servers are used for getting correct domain which contains the numerical IP address of the website being sought.
Local DNS servers are usually located on the network to which your device is connected. Functionality of Local DNS is discussed in working of DNS section.
Conclusion
The Domain Name System is a critical infrastructure that simplifies internet usage, making it user-friendly and efficient. It plays a vital role in translating human-readable domain names into machine-readable IP addresses, offering a range of services that enhance network performance, reliability, and security. Understanding how DNS works is essential for network administrators and anyone interested in the functioning of the internet.
