DNS Server Not Responding? 5-Step Complete Troubleshooting Guide [2025 Updated]

Introduction: Can't Connect to Internet? It Might Be a DNS Problem

Opening a webpage, but getting a "DNS server not responding" error message.

Don't panic. This is one of the most common network issues, and usually you can fix it yourself within 3 minutes.

This article will teach you:

• What is DNS, and why does it have problems
• 5 steps to troubleshoot DNS issues
• Complete operation tutorials for Windows and Mac
• Recommended DNS server settings

Follow along and solve the problem immediately.

Having trouble fixing it quickly? 👉 Book a free consultation, let an expert help

Part 1: What Is a DNS Server?

Before troubleshooting, quickly understand what DNS is.

DNS Function

DNS (Domain Name System) is like the phone book of the internet world.

What you remember is the URL: www.google.com What computers recognize is the IP: 142.250.185.78

DNS servers are responsible for "translating" URLs into IP addresses so computers know where to connect.

DNS Query Process

1. You type www.google.com in browser
        ↓
2. Computer asks DNS server: "What's the IP for www.google.com?"
        ↓
3. DNS server answers: "142.250.185.78"
        ↓
4. Computer connects to 142.250.185.78
        ↓
5. Google homepage appears on your screen

The entire process only takes tens of milliseconds.

Why Does "DNS Server Not Responding" Appear?

When this translation process has problems, you'll see error messages. Common causes include:

Cause	Description	Probability
DNS server failure	ISP's DNS server crashed or overloaded	High
Network device issues	Router or modem malfunction	High
DNS cache corruption	Locally stored DNS data has problems	Medium
Firewall blocking	Security software blocking DNS requests	Medium
Network settings error	IP or DNS settings incorrect	Low
Network cable/WiFi issues	Physical connection problems	Low

Good news: In most cases, changing to a different DNS server solves it.

Want to learn more about DNS and other server types? Refer to Server Types Complete Analysis: 7 Common Server Types Compared

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Part 2: Common Causes of DNS Server Not Responding

2.1 ISP's DNS Server Failure

The most common cause. ISP-provided DNS servers occasionally have problems.

Characteristics:

• Suddenly can't connect to internet
• Mobile data on phone works
• Other devices on same network also can't connect

Solution: Change to public DNS (like Google DNS, Cloudflare DNS)

2.2 Router/Modem Issues

Network devices may accumulate errors or run out of memory after running for a while.

Characteristics:

• Can't connect to internet
• Router indicator lights abnormal
• Normal after restart

Solution: Restart router and modem

2.3 DNS Cache Corruption

Computers store queried DNS results (cache) to speed up future queries. But cache can expire or corrupt.

Characteristics:

• Some websites can't connect, others work fine
• Different browser works
• Direct IP connection works, URL doesn't

Solution: Clear DNS cache

2.4 Firewall or Security Software Interference

Antivirus software, firewalls may mistakenly block DNS requests.

Characteristics:

• Problem appeared after installing new software
• Problem appeared after updating antivirus
• Works after temporarily disabling firewall

Solution: Check firewall settings, add exceptions

2.5 Network Card Driver Issues

Network card drivers outdated or corrupted.

Characteristics:

• Problem appeared after Windows update
• Device Manager shows network card has issues
• Other computers on same network work fine

Solution: Update or reinstall network card drivers

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Part 3: Solution Step-by-Step Tutorial

Here are 5 steps to try in order—usually the first 3 steps solve the problem.

Step 1: Check Network Connection

First confirm whether the problem is DNS or the entire network is down.

Check Method:

1. Check if router/modem indicator lights are normal
2. Check if network cable is plugged in properly (if wired)
3. Confirm WiFi is connected
4. Test if other devices can access internet on same WiFi

If other devices can access internet: Problem is with your computer, continue to next step.

If all devices can't access internet: Problem is with network equipment or ISP, jump directly to Step 4 to restart devices.

Step 2: Clear DNS Cache

Clear the DNS cache stored on the computer, making the computer re-query.

Windows Operation:

1. Press Win + R to open Run dialog
2. Type cmd, press Enter
3. In Command Prompt, type the following command:

ipconfig /flushdns

4. Seeing "Successfully flushed the DNS Resolver Cache" means success

Mac Operation:

1. Open "Terminal" (in Applications → Utilities)
2. Type the following command:

sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder

3. Enter computer password, press Enter
4. No error message means success

After clearing, reopen browser and test.

Step 3: Change DNS Server

This step is usually most effective. Change DNS from ISP default to public DNS.

Recommended DNS Servers:

DNS Service	Primary DNS	Secondary DNS	Features
Google DNS	8.8.8.8	8.8.4.4	Stable, most widely used globally
Cloudflare DNS	1.1.1.1	1.0.0.1	Fastest, privacy protection
Quad9	9.9.9.9	149.112.112.112	Security filtering for malicious sites

Recommendation: Google DNS (8.8.8.8) or Cloudflare DNS (1.1.1.1)

If you're considering setting up your own DNS server or home server, refer to Home Server Setup Guide: Building Your First Server from Scratch

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Windows 11/10 Change DNS Tutorial:

1. Right-click network icon in taskbar → "Network & Internet settings"
2. Click "Advanced network settings"
3. Click the network you're using (WiFi or Ethernet)
4. Click "View additional properties"
5. Find "DNS server assignment," click "Edit"
6. Select "Manual"
7. Turn on "IPv4"
8. Fill in:
   • Preferred DNS: 8.8.8.8
   • Alternate DNS: 8.8.4.4
9. Click "Save"

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Mac Change DNS Tutorial:

1. Click Apple icon top left → "System Settings"
2. Click "Network"
3. Select the network you're using (WiFi or Ethernet)
4. Click "Details"
5. Click "DNS"
6. Click "+" to add DNS servers:
   • 8.8.8.8
   • 8.8.4.4
7. Click "OK" to save

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After setup, reopen browser and test.

Part 6: FAQ

Q1: What does "DNS server not responding" mean?

It means your computer can't connect to the DNS server, can't translate URLs (like www.google.com) into IP addresses. Without this translation, you can't connect to websites.

Q2: Why do DNS problems suddenly appear?

The most common cause is ISP's (Internet Service Provider's) DNS server temporarily failing. Changing to Google DNS (8.8.8.8) usually solves it.

Q3: Which is better, Google DNS or Cloudflare DNS?

Both are great:

• Google DNS (8.8.8.8): Stable, most widely used globally
• Cloudflare DNS (1.1.1.1): Fastest, better privacy protection

Recommend trying Google DNS first, if there are issues switch to Cloudflare.

Q4: Does changing DNS affect internet speed?

Usually it gets faster. Public DNS (like Google, Cloudflare) response time is usually faster than ISP defaults. Actual difference is about 10-50 milliseconds, generally not noticeable in normal use.

Q5: What if ISP's DNS server is not responding?

Just switch to Google DNS (8.8.8.8) or Cloudflare DNS (1.1.1.1). This is the quickest solution.

If your ISP's DNS is failing, switching to public DNS bypasses the problem.

Q6: Still can't connect after changing DNS?

1. Confirm your network itself is normal (router lights, other devices)
2. Restart router and modem
3. Clear DNS cache
4. Check firewall settings
5. If nothing works, might be ISP line issue, contact customer service

Q7: How to restore automatic DNS?

Windows:

1. Network settings → DNS server assignment → Change back to "Automatic (DHCP)"

Mac:

1. Network settings → DNS → Delete manually added DNS servers

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Part 7: Further Reading

After solving DNS problems, you might be more interested in servers and networking:

• Server Complete Guide: From Beginner to Enterprise Applications
• Server Types Complete Analysis: 7 Common Server Types Compared
• Home Server Setup Guide: Building Your First Server from Scratch
• Server Pricing Guide: Complete Pricing from Entry to Enterprise Level

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Part 8: Still Can't Fix It? Let an Expert Help

If you've tried all the above methods and the problem still exists, it might be a deeper network or device issue.

Possible Causes Include:

• Router hardware failure
• ISP line issues
• Network card hardware problems
• Malware infection
• Special enterprise network settings

CloudInsight Can Help You:

• Remote network problem diagnosis
• Enterprise network architecture consultation
• Network equipment purchase recommendations
• Long-term IT support services

Consultation Is Completely Free

Network problems troubling you? Let an expert help find the root cause.

👉 Book free consultation, let an expert help solve your network problems

We'll respond within 24 hours.

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References

1. Microsoft, "Troubleshoot DNS Client Issues" (2024)
2. Apple Support, "Change DNS Settings on Mac" (2024)
3. Google Public DNS, Documentation
4. Cloudflare, "1.1.1.1 DNS Resolver"