DNS 101: From Googling 'What Is A Nameserver' to Feeling Kinda Smart

 

If you're like me, you probably spend some time on YouTube watching how bridges are built. So I hop onto my browser, type in 153.251.208.65, and find myself a video. Usually, my grandma types up 8.8.8.8 to figure out if what she heard about an outbreak is actually true.

Okay, nobody does that. Most of us barely remember boituxz.netlify.app, let alone a 192... Fortunately, we don't have to, thanks to a big unsung hero making sure you end up at the right place.

Over the last few weeks, I've slowly moved deeper into the world of backend—from typing localhost in my API requests to 127.0.0.1. Both of those lead to the same place, but it made me beg the question: how? Which brought me to another question: beyond my localhost, what else is going on?

This is what gave birth to the post you're reading—planned as a two-part series exploring What's the Web? by looking at DNS and HTTP.

So what's the DNS?

The Domain Name System is what a GPS is to a road user. Simply put, it keeps a record of domain names and the IP addresses they belong to. For example, in my earlier example, 8.8.8.8 is for Google. This makes life easier for us users, so we can access websites without having to cram long strings of numbers.

So DNS stores domains. What are domains?

Think of them as an address to a website on the internet. These domains consist of three parts: Top-Level Domain, Second-Level Domain, and Root Domain.

Top-Level Domain (TLD)

This is the part on the right of your domain—your .com, .org, .zw. Notably, there are two types: gTLD and ccTLD.

The former (generic Top-Level Domain) was initially made to tell you what the website is for—so .com for commercial sites, .gov for government sites, and so on. But due to increased demand, we now have .online, .me, .name, .biz, so that may no longer be the case where the ending strictly represents what the site is for.

ccTLDs (country code Top-Level Domains) are simpler. As the name suggests, they are for a specific region. That means .zw for Zimbabwe and so on.

Funny enough—has anyone come across a .us TLD? Let me know.

\Root Domain

The dot (.).
Yeah, that's it.

Second-Level Domain (SLD)

Much more interesting than the root domain, this is the google in google.com, the linkedin in linkedin.com. This is what we fuss over when registering a domain—trying to juggle something catchy, wanting your name as a domain, and then finding out boitumelo.com is $2000. Yikes.

This part of the domain is limited to 63 characters and must consist of letters, hyphens, and numbers only—A-Z and 0-9. They also can't start or end with hyphens or have consecutive hyphens. So no www.-Boitumelo.com. Believe me, I tried.

Subdomain

These are found to the left of the Second-Level Domain—think admin.tryhackme.com. They have the same restrictions as above.

Subdomains serve the purpose of organizing and separating different sections of a website, allowing for distinct content or functionality without needing a separate domain name. They help improve website navigation, target specific audiences, and can be useful for localized content or niche areas.

The MAGIC

So you've typed in your URL—maybe to your API or just google.com. What happens now?

Your computer checks its local cache to see if it has the address of that domain. This is why websites you've visited before are found faster—not loaded faster, that’s a different cache.

If nothing is found, it goes to the next level: a recursive DNS server, usually provided by your ISP. This server has a cache as well, and for popular sites like Google, the journey usually ends here.

But what if you want to check out my blog, which doesn't have that many readers? 😂
Well, we go further.

If nothing is found in the recursive server, then we move to the root server. These just direct you to a TLD server. So if your site ends in .org, the root server sends you to the TLD server that handles .org.

These TLD servers then direct you to an authoritative server—this one finally answers your plea for help. An authoritative server stores DNS records of a domain and any updates made to that domain name. The answer is returned to your computer, and you get your site.

A TTL (Time To Live) value comes with the domain records—it determines how long the name should be cached before being cleared.

Oh, and there’s more—there are different types of DNS records

Records

• A Records resolve to IPv4 addresses

• AAAA Records resolve to IPv6 addresses

• MX Records point to mail servers (for email)

• TXT Records are text fields where any data can be stored

• CNAME Records resolve to another domain

So that summarizes the map of the internet—that’s the DNS

 Let me know when you’re ready for part two: HTTP - The Internet’s Waiter