IT Foundations · Lesson 1
How DNS helps your browser find a website
Outcome: In about 12 minutes, you will be able to explain what DNS does and what happens before a browser contacts a website.
The problem: names are easier than numbers
You type example.com into a browser. Your device cannot find a server from that name alone; network communication uses an Internet Protocol address, usually called an IP address.
Remembering a readable name is easier than remembering an address such as 93.184.216.34. The Domain Name System, or DNS, connects these two forms.
Use one picture: an address book
Imagine saving a person as “Maya” in your contacts. You select the name; your phone uses the stored number.
DNS plays a similar role:
- Domain name: the readable name, such as
example.com. - IP address: the network address used to reach a server.
- DNS lookup: the process of asking for the information connected to the domain.
The analogy has a limit: DNS is not one global file on one computer. It is a distributed system made of many servers and delegated parts.
What happens during a lookup
Your device usually asks a recursive resolver to find the answer. The resolver may already have a valid cached answer. If not, it follows referrals through the DNS hierarchy until it reaches an authoritative source for the domain.
- 1. BrowserNeeds the address for a domain
- 2. ResolverChecks its cache first
- 3. RootPoints toward the top-level domain
- 4. TLDPoints toward the domain's nameserver
- 5. AuthorityReturns the relevant DNS record
Three supporting ideas
- Distributed: DNS information is spread across many independently operated servers.
- Hierarchical: names are organized in levels, such as the root,
.com, andexample.com. - Cached: resolvers can temporarily store answers according to their time-to-live value.
Worked example: opening example.com
example.com is reserved for documentation, so it is safe to use in examples.
- You enter
https://example.com. - Your device asks its configured DNS resolver for the address connected to
example.com. - The resolver returns a cached answer or obtains the answer through DNS nameservers.
- Your browser uses the returned address to contact the server.
- HTTPS then protects the web connection and the server returns webpage data.
DNS participates in finding where to connect. It does not itself download, secure, or display the webpage.
Do not mix up these jobs
| Term | Main job | Address-book comparison |
|---|---|---|
| Domain name | A human-readable name | The contact name |
| DNS | Finds records connected to the name | Looking up the contact |
| IP address | Identifies a network destination | The phone number |
| HTTPS | Protects communication with the website | A private, protected call |
| Web hosting | Runs or stores the website content | The person or organization you reach |
Try it in under three minutes
Option A: Explain aloud: “DNS is useful because…” Keep the explanation under 30 seconds.
Option B on a Mac: Open Terminal, enter nslookup example.com, and press Return. Look for an address in the result. The exact address may vary because services can use multiple addresses and delivery systems.
You do not need to memorize the lookup commands. The goal is to connect a readable name with a returned network address.
Three-line recap
- DNS connects domain names with records that computers use, including IP addresses.
- A resolver checks cached information and, when needed, follows the DNS hierarchy toward an authoritative answer.
- DNS finds where to connect; HTTPS and the browser perform different jobs.
Communication practice
Complete this sentence in plain language:
A good explanation mentions a readable name and the address used to reach a server. It does not need to mention every type of nameserver.
Your review plan
These dates bring the central idea back with a different question. Check a box only after completing that review.
Sources and fact check
- ICANN: The Domain Name System. Official overview of domain names, IP addresses, and DNS.
- Cloudflare Learning Paths: What is DNS?. Lookup sequence, resolvers, caching, and authoritative nameservers; page updated 23 April 2026.
- RFC 1034: Domain Names, Concepts and Facilities. Foundational Internet standard describing the distributed, hierarchical DNS design; published November 1987.
- RFC 2606: Reserved Top Level DNS Names. Confirms that
example.comis reserved for documentation; published June 1999.
Sources checked 14 July 2026. Older RFCs are used because they define stable protocol foundations; the current explanatory documentation was checked for modern terminology and behavior.
Q&A: answer before you reveal
Write whatever you remember. The attempt matters more than perfect wording, and your text stays saved in this browser.
Finished for today?
You only need the central idea today. The review schedule will bring the details back.