DNS Explained: Why It’s Often the Reason Sites Go Down

If you’ve ever tried to visit a website and been greeted with an error message saying something like “This site can’t be reached” or “Server not found”, you’ve probably experienced a DNS issue without even realising it. DNS problems are one of the most common reasons websites go down, yet they’re also one of the least understood. Let’s break it down in plain English.

What Is DNS, Really?

DNS stands for Domain Name System — often called “the phonebook of the internet.” When you type a web address like google.com into your browser, your computer doesn’t actually understand that name directly. Computers talk in IP addresses (strings of numbers like 142.250.183.206), which tell your device exactly where to find the website’s server.

DNS is the translator between the human-friendly web address you remember and the numeric IP address that computers use. Without it, you’d have to memorize dozens (or hundreds) of long strings of numbers just to browse your favorite sites.

Here’s a simple analogy:

  • You: “I want to visit Google.”
  • DNS: “Sure, the address is 142.250.183.206 — I’ll take you there.”

This process happens in milliseconds, and you never even notice it… unless something goes wrong.

How DNS Works Behind the Scenes

When you visit a website, here’s a simplified version of what happens:

  1. You type a URL into your browser.
  2. Your browser checks its cache to see if it recently looked up the IP address for that domain. If it has, it uses that. If not, it asks your operating system.
  3. Your operating system asks your DNS resolver — usually provided by your internet service provider (ISP) or a third-party DNS service like Google DNS (8.8.8.8) or Cloudflare DNS (1.1.1.1).
  4. The resolver contacts root DNS servers to find out where to look for the domain’s records.
  5. It then talks to the domain’s authoritative nameservers — the servers that have the final say on the correct IP address.
  6. The resolver passes the IP address back to your browser, which connects to the website’s server.

All of this happens in a fraction of a second. But if any part of this chain fails, the site won’t load.

Why DNS Problems Can Take a Site Down

DNS is like a switchboard operator. If it’s not functioning correctly, your request to visit a site simply can’t find where to go. Here are the most common DNS-related reasons websites go offline:

1. Nameserver Issues

If a site’s authoritative nameservers are down or misconfigured, your computer won’t be able to find its IP address. This is a frequent cause of outages, especially for smaller sites that host their DNS with a single provider and don’t have redundancy.

2. DNS Propagation Delays

When a domain changes hosting providers or IP addresses, the DNS records have to be updated worldwide. This process, called propagation, can take anywhere from a few minutes to 48 hours. During that time, some users may still be directed to the old (possibly offline) server.

3. Expired Domains

If a domain owner forgets to renew their registration, the DNS records vanish when the domain goes inactive. Until the domain is renewed, the site is unreachable.

4. Incorrect DNS Records

Even a small typo in a DNS record — like entering the wrong IP address — can take a site offline instantly. It’s the digital equivalent of writing down the wrong house number for your friend’s address.

5. DNS Provider Outages

Sometimes, the issue isn’t with the website itself but with the DNS service that hosts its records. In 2020, a Cloudflare DNS outage temporarily disrupted access to multiple major websites.

6. DDoS Attacks on DNS

Distributed denial-of-service (DDoS) attacks target DNS servers to overwhelm them with traffic, making it impossible for legitimate users to get an IP address. The infamous Dyn DNS attack in 2016 temporarily broke access to Netflix, Twitter, Reddit, and other big names.

How to Tell If a Site Is Down Because of DNS

If you’re trying to troubleshoot whether a website is down for everyone or just you, there are a few signs that point toward DNS:

  • The error message says something like “server not found” or “DNS address could not be found.”
  • You can reach the site by typing its IP address directly into your browser but not by its domain name.
  • A DNS checker tool (like dnschecker.org) shows missing or mismatched DNS records.

Sometimes, using a different DNS provider (such as Google’s 8.8.8.8 or Cloudflare’s 1.1.1.1) can get you back online faster if your ISP’s DNS resolver is having problems.

Why DNS Outages Can Be Tricky to Fix

Unlike a web server outage — where the hosting provider can usually restore service quickly — DNS problems can linger. That’s because DNS records are cached at multiple levels: your browser, your operating system, your ISP, and DNS resolvers worldwide. Even after fixing a record, it may take hours for the change to reach everyone.

Another challenge is that DNS issues are often invisible to non-technical users. If a site loads for some people but not others, it can cause confusion and make the problem harder to diagnose.

How Website Owners Can Prevent DNS-Related Downtime

If you own or manage a website, you can reduce the risk of DNS issues by following a few best practices:

  1. Use a reliable DNS provider — Preferably one with a proven track record and multiple redundant servers in different locations.
  2. Enable DNS redundancy — Host your records with more than one DNS provider so if one goes down, the other takes over.
  3. Monitor your DNS — Use tools that alert you if your DNS records change unexpectedly or if nameservers stop responding.
  4. Keep your domain registration current — Set up auto-renewal so you never lose your domain by accident.
  5. Use a CDN with DNS failover — Services like Cloudflare or Akamai can help reroute traffic automatically during outages.

The Bottom Line

DNS is the silent hero of the internet — and sometimes its silent villain. Most people never think about it until it stops working, but without it, the web as we know it wouldn’t function.

The next time a site won’t load, remember: it might not be your internet connection, your device, or even the website’s server. It could be that the internet’s phonebook — DNS — is having a bad day.

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