DNS Server Unavailable: What It Means and How to Fix It

When you see the message “DNS server unavailable”, it means that your device is unable to communicate with the DNS Service (Domain Name System) server, which is responsible for translating domain names (like example.com) into IP addresses that computers use to locate websites. This error prevents you from accessing websites because your device can’t resolve domain names into IP addresses.

In this article, we’ll explain what the DNS server unavailable error means, its common causes, and how to troubleshoot and resolve the issue.

What Does “DNS Server Unavailable” Mean?

The DNS (Domain Name System) is like the phonebook of the internet, translating user-friendly domain names into machine-readable IP addresses. When the DNS server is unavailable, your device cannot resolve domain names, which leads to errors when you try to access websites.

This issue can occur due to various reasons, including network configuration problems, issues with your internet service provider (ISP), or problems with your device.

Common Causes of the DNS Server Unavailable Error

Several factors can contribute to the DNS server unavailable error:

1. DNS Server Outage

The DNS server provided by your ISP might be down or experiencing heavy traffic, making it temporarily unavailable.

2. Network Configuration Issues

Incorrect network settings on your computer or router could prevent your device from connecting to a DNS server.

3. Firewall or Antivirus Interference

Sometimes, security software (firewalls or antivirus programs) can block DNS requests, causing connection problems.

4. Router or Modem Issues

Problems with your router or modem, such as outdated firmware or incorrect DNS settings, can disrupt the connection to the DNS server.

5. Incorrect DNS Settings

Manually configured DNS settings on your computer or router might be pointing to the wrong DNS server.

How to Fix the DNS Server Unavailable Error

Here are several methods you can try to resolve the DNS server unavailable error:

1. Restart Your Router and Modem

The simplest solution is often the most effective. Restarting your router and modem can refresh your internet connection and resolve any temporary issues.

Steps:

1. Turn off your modem and router by unplugging them from the power source.
2. Wait 30 seconds, then plug them back in.
3. Wait for the devices to fully reboot, and check if the issue is resolved.

2. Flush DNS Cache

Your computer stores IP addresses of websites in a DNS cache to speed up access. Sometimes, this cache can become corrupted, leading to DNS issues. Flushing the DNS cache can help resolve this.

Steps (Windows):

1. Press Windows + R, type cmd, and press Enter to open the Command Prompt.
2. In the Command Prompt, type the following command and press Enter:
   ipconfig /flushdns
3. Once completed, restart your browser and try accessing the website again.

Steps (macOS):

1. Open the Terminal (press Command + Space and type Terminal).
2. In the terminal, type the following command and press Enter:
   sudo killall -HUP mDNSResponder
3. Enter your password if prompted, then try reconnecting.

3. Change DNS Server Settings

If the DNS server provided by your ISP is causing the problem, you can manually change your DNS server settings to use a reliable public DNS service like Google DNS or Cloudflare DNS.

Steps (Windows):

1. Open the Control Panel and go to Network and Sharing Center.
2. Click on Change adapter settings on the left side.
3. Right-click on your active internet connection and select Properties.
4. Select Internet Protocol Version 4 (TCP/IPv4) and click Properties.
5. Choose Use the following DNS server addresses and enter the following:
   • Preferred DNS server: 8.8.8.8 (Google DNS) or 1.1.1.1 (Cloudflare DNS)
   • Alternate DNS server: 8.8.4.4 (Google DNS) or 1.0.0.1 (Cloudflare DNS)
6. Click OK to save the changes.

Steps (macOS):

1. Go to System Preferences > Network.
2. Select your active network connection and click Advanced.
3. Go to the DNS tab.
4. Click the + button and add the following DNS servers:
   • 8.8.8.8 (Google DNS) or 1.1.1.1 (Cloudflare DNS)
   • 8.8.4.4 (Google DNS) or 1.0.0.1 (Cloudflare DNS)
5. Click OK and then Apply to save the settings.

4. Disable Antivirus or Firewall Temporarily

Disabling your antivirus or firewall temporarily can help diagnose if these security programs are causing issues with your DNS connections. Sometimes, security software can block certain network traffic, including DNS requests, thinking they are a potential threat. By disabling them temporarily, you can rule out whether these programs are interfering with your connection. However, keep in mind that this should be done cautiously, and you should only temporarily disable the firewall or antivirus to troubleshoot the issue. Always ensure to re-enable them after testing to maintain the security of your system.

Here’s a detailed guide on how to disable Windows Defender Firewall to help troubleshoot DNS issues:

Steps to Disable Windows Defender Firewall Temporarily

1. Open Control Panel

• Press the Windows key on your keyboard or click the Start menu in the bottom left corner of your screen.

• Type Control Panel into the search bar and select the Control Panel app from the search results.

2. Navigate to System and Security

• In the Control Panel window, look for and click on System and Security. This will take you to a page where you can adjust your system’s security settings, including Windows Defender Firewall.

3. Access Windows Defender Firewall Settings

• On the System and Security page, click on Windows Defender Firewall. This will open the settings for your firewall.

4. Turn Off Windows Defender Firewall

• In the left pane of the Windows Defender Firewall window, click on Turn Windows Defender Firewall on or off.

• You’ll be presented with options to turn off the firewall for both private and public networks. Select the option Turn off Windows Defender Firewall (not recommended) for both networks.

• After selecting this option, click OK to apply the changes.

5. Test Your Internet Connection

• With the firewall disabled, try accessing websites or testing your DNS connection to see if the issue persists. You can open a browser and try navigating to a website, or use the Command Prompt to perform a DNS lookup.

After testing, make sure to enable your antivirus or firewall again for security.

Resetting the TCP/IP stack is a reliable troubleshooting method that can fix a variety of network-related problems, including persistent DNS errors, limited connectivity, or issues after malware removal. The TCP/IP stack is a set of networking protocols that allow your computer to communicate over the internet, and if any part of this stack becomes corrupted or misconfigured, you may experience connectivity issues. By resetting it, you essentially return the settings to their default state, which often resolves conflicts or misconfigurations caused by third-party software or incorrect manual settings.

Steps to Reset the TCP/IP Stack on Windows

1. Open Command Prompt as Administrator:
   Press Windows + X and choose Command Prompt (Admin) or Windows PowerShell (Admin) from the menu. You can also search for “cmd” in the Start menu, right-click it, and choose “Run as administrator”.

2. Enter the Following Commands (press Enter after each one):

   netsh int ip reset
netsh winsock reset


   • The first command resets the Internet Protocol (IP) settings, including static IP addresses and default gateway entries.

   • The second command resets the Winsock catalog, which handles network requests and is often a source of connectivity problems when corrupted.

3. Restart Your Computer:
   This step is essential to apply the changes made by the reset commands. Once the system reboots, your network configuration will be refreshed, and any temporary issues should be resolved.

After rebooting, try reconnecting to the network and check whether the DNS or connectivity issue has been fixed. If problems persist, consider additional troubleshooting steps such as flushing the DNS cache, updating network drivers, or checking for firewall conflicts.