If you use the internet much at all, then this error code might look familiar to you:

Usually, a quick page refresh or a refined keyword search in your favorite search engine will fix the problem and get you to the page you want. However, if you keep seeing error code 404, your DNS Server might be to blame. A simple network diagnostic test should tell you whether or not this is the case. If so, then don’t worry! There are several possible ways to fix the issue so you can get back to surfing the web in no time.

What is a DNS Server?

DNS stands for Domain Name System. A DNS server holds a vast database where each website’s different IP addresses connect to a domain name. Let’s look at what the parts of a URL are in order to understand this more clearly. We will use https://www.forbes.com as an example. There are four components to this URL that make it unique to the IP address that locates it.

1. The Protocol: https://

The other option you might see is “http.” This is for a website that does not have secure data interaction. Users should be aware that http sites are less trustworthy and make a user more susceptible to having their personal information compromised. Website owners can quickly resolve this by purchasing an SSL certificate.

2. The Subdomain: www.

Another example of a subdomain would be https://mail.google.com where “mail.” is the subdomain within the site’s primary domain name.

3. The Term: forbes

The term is the “name” portion of a domain name, or what we would typically think of as the company name, brand name, etc. on a website.

4. The Top-Level Domain: .com

We typically see .com as a Top-Level Domain (TLD) most often in the United States. There are different kinds of TLDs, such as generic TLDs (gTLDs) and country-code TLDs (ccTLD). An example of a ccTLD would be .uk or .africa. An instance of a gTLD would be .com or .net. Some of these new gTLDs even require accreditation, which offers an added sense of security to let users know a site is trustworthy. For example, only an accredited bank can purchase a .bank domain. To do so, they need provide verification of their accreditation to a .bank domain registrar, like 101domain.

I will be referring to the combination of the “term” and the “top-level domain” (in number 3 and 4) together as the “domain name.” These are the pieces of the URL that one would typically type into the browser in order for a computer to request the correlating IP address for that domain name from the DNS.

The use of a complete URL, or a domain name and a DNS Server allow us greater ease in surfing the web so that we don’t have to memorize or manually keep a record of website IP addresses as we typically do with phone numbers.

For example, if I want to complete a Google Search, I can type “www.google.com” into my browser instead of having to type “http://74.125.230.243.” The domain name acts as a keyword that is sent to the DNS Server to locate the IP address within the database. The correlating IP address to that specific domain name is then stored in your system’s DNS cache so that you can access the website with higher speed the next time you wish to do so.

How Does the Server Become Unresponsive?

Here are a few potential problems that could be the culprit of your DNS Server issues:

  • The DNS cache needs to be “flushed,” or cleared
  • Malware might have poisoned your DNS cache
  • The current DNS server in use may need to be switched over to a more reliable DNS Server

How Can I Resolve the DNS Server Issue?

The first thing that you should try in order to resolve this concern is clearing the DNS cache on your system. Sometimes a website will update the IP address associated with its domain name and if you have not cleared your DNS cache in a long time, your system could be holding on to old IP addresses that are no longer accurate in regards to that domain name. In that case, an incorrect IP address would send you to a nonexistent page even if you type the correct domain name into your browser.

Windows

To clear DNS cache:

  1. Launch the command prompt as an administrator
  2. Enter: ipconfig/flushdns
  3. Exit the application and restart the computer

If you find a domain name redirects you to a suspicious site or scam, malware may have poisoned your DNS cache. In this case, you should download and use a trustworthy anti-malware application to get rid of it. If that is not the issue, then you may have to switch the DNS Server to a more reliable one.

macOS

To clear DNS cache:

  1. Launch the terminal
  2. Enter: sudo killall -HUP mDNSResponder
  3. Exit the application and restart the computer

To switch the DNS Server to OpenDNS (another free and reliable DNS server):

  1. Open System Preferences
  2. Choose Network
  3. Select your network connection
  4. Click on Advanced
  5. Choose DNS
  6. Remove the existing DNS IPs
  7. Add 208.67.222.220 to the DNS Servers column
  8. Repeat step 7 using 208.67.222.222

There are also anti-malware applications for Mac that you can download if necessary. Please refer to the “Windows” section of this article for more details.

How Can I Change DNS Server?

Below are instructions to switch to Google’s public DNS Server:

  1. Launch control panel
  2. Click on “Network and Internet”
  3. Choose “Network and Sharing Center”
  4. Click on “Change Adapter Settings”
  5. Right-click “Network Adapter” + select “Properties”
  6. Select “Internet Protocol 4” [tcp/ipv4]
  7. Click on “Properties”
  8. Select “Use the Following DNS Server Addresses”
  9. Enter 8.8.8.8 In the space for Preferred DNS type
  10. Enter 8.8.4.4 In the space for Alternate DNS type
  11. Press okay and restart your computer

Following these steps should get your DNS Server responding again in no time.

Happy browsing!

Tom Parillo

Tom Parillo

I am interested in all things technology, especially automation, robotics and tech that helps change how society will live in the future.
Tom Parillo

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