The Core Problem

Our computers only understand 0 and 1. When we search for google.com, computers don’t have any idea what is written here. To find the website, they need a unique identifier, and that is the IP address of the website, which is stored by DNS.

What is the Domain Name System?

• DNS holds the IP address of the website and maps the domain name to its authoritative servers, resolving the domain name by looking up these stored records.

• In simple language, you can understand DNS like the internet’s phonebook.

• DNS translates a domain name into an IP address, allowing browsers to access information on the Internet.

• Without DNS, we need to remember IP’s which is next to impossible for humans, and then the internet becomes unusable for us.

Why does name resolution exist?

• Name resolution is a process to find the IP address of a domain name, and the entire journey is known as DNS resolution.

• It is important because without name resolution, we need to remember IPs manually.

➡️ Now, let’s understand how DNS resolution works??

Step:1 Browser

• Searching: https://google.com

• Browsers don’t have any Ip itself, it asks the operating system - “Did you know the Ip of google.com?“

Step:2 OS

• The operating system then checks in two places: Browser cache and the OS cache.

• If it finds it passes to the browser; otherwise, it raises a request for DNS packets to the router.

Step:3 Router

• It receives DNS packet requests and looks at the destination IP.

• Forward packets to the ISP.

Step:4 ISP

• ISP directs the request to its DNS resolver.

Step:5 DNS Resolver

• It first checks its own cache

• if not found:

  1. Ask the Root Server

  2. then .com TLD server

  3. Then Google’s authoritative server.

➡️ After these steps, the IP is transferred back to the browser from the same path it came from.

What is the dig Command and when it is used?

Let’s understand why we need this command, what the dig command is, and its working.

Why we need dig Command?

• We knew DNS works behind the scenes, and that’s why we never see,

  • Which DNS server replied

  • Which record was used

  • Where the answer came from

• So, how does a developer see what DNS is actually doing??

What is dig?

• dig stands for Domain Information Groper.

• dig is a command-line tool that lets you directly ask DNS servers questions and see their raw answers.

You can ask things like:

1. What is the IP of this domain?

2. Who is authoritative for this domain?

3. What are the name servers?

4. What DNS record exists?

   ➡️Anything related to DNS, you can ask with dig command.

DNS Hierarchy: How DNS Servers Are Organized

DNS is a hierarchical naming system that translates human-readable domain names into IP addresses.

Understanding dig.NS and Root Name Servers

What Does . Mean in DNS?

In DNS:

. = ROOT

• The dot (.) represents the root of the DNS hierarchy

• Every domain ends with a dot (it’s just hidden)

• Example: google.com.

• The last dot means: “Start at the root of DNS.”

What Are Root Name Servers?

• Root name servers are the starting point of DNS resolution.

• They sit at the top of the DNS hierarchy

• They know where TLD servers are

• They do NOT know the IPs of websites

• They only answer: “Which servers handle .com, .org, .net, etc.?”

Run This Command:

dig . NS

dig . NS @1.1.1.1

• These are Root DNS servers

• Managed by different organizations

• Globally distributed

• There are 13 logical root servers (A–M).

When running dig . NS, the query may fail if the system is using a home router as its DNS server. Consumer routers typically act as DNS forwarders and may not support root-level DNS queries, resulting in a SERVFAIL response. Querying a public DNS resolver such as Google (8.8.8.8) or Cloudflare (1.1.1.1) bypasses this limitation and returns the root name server records correctly.

Understanding dig com NS and TLD Name Servers

TLD = Top-Level Domain

Examples:

• .com

• .org

• .net

• .in

TLD name servers know which authoritative servers are responsible for a domain.

“For google.com, ask these authoritative servers.”

Run This Command

dig com NS @8.8.8.8

These are:

• .com TLD name servers

• Operated under ICANN

• Globally distributed

These servers handle ALL .com domains:

• google.com

• amazon.com

• facebook.com

• millions more

Understanding dig google.com NS

Authoritative Name Server

An authoritative name server is the source of truth for a domain.

• It is controlled by the domain owner

• Stores actual DNS records:

  • A

  • AAAA

  • MX

  • CNAME

• Gives final answers, not directions

Run This Command:

dig google.com NS @8.8.8.8

These servers:

• Are owned by Google

• Answer all DNS questions for google.com

• Store the actual records

Authoritative name servers are responsible for storing and serving the actual DNS records of a domain. Unlike root and TLD servers, authoritative servers provide final answers to DNS queries, including IP address mappings. These servers are operated by the domain owner or their DNS provider.

Understanding dig google.com

When you run:

dig google.com

You are asking:

“Show me the final DNS answer for google.com, after the entire DNS hierarchy has done its job.”

DNS resolution is not a single lookup but a structured, hierarchical discovery process. When a user enters a domain name such as google.comThe browser relies on a DNS resolver to navigate the global DNS hierarchy, starting from the root name servers, moving through the appropriate top-level domain (TLD) servers, and finally reaching the authoritative name servers that store the actual DNS records.

Tools like dig allow us to observe this otherwise invisible process. By querying root servers (dig . NS), TLD servers (dig com NS), and authoritative servers (dig google.com NS) We can see how responsibility is distributed across different layers of DNS. The final query (dig google.com) demonstrates the outcome of this entire flow: the IP address that browsers use to establish network connections.

This hierarchical design makes DNS scalable, reliable, and fast, even at the scale of the global internet. Understanding DNS resolution not only demystifies how browsers locate websites but also provides a strong foundation for deeper topics in networking, system design, and web infrastructure.

Once you understand DNS, the internet stops feeling like magic and starts feeling like engineering.

Feedback Request:

“I’m a beginner learning computer science. If you’re experienced, I’d really appreciate feedback on clarity, accuracy, and structure. Be honest, it’ll help me improve.”