Troubleshooting DNS Problems: A Practical Guide

"This site can't be reached" - we've all seen that error. Often, DNS is the culprit. Here's how to figure out what's wrong and fix it.

Step 1: Is It Actually DNS?

First, let's confirm DNS is the problem. Try visiting a website by its IP address instead of domain name. If that works but the domain doesn't, you've got a DNS issue.

You can also try: - Different browser (rules out browser cache) - Different device on same network (rules out device-specific issues) - Mobile data instead of WiFi (rules out network issues)

Step 2: Check Your DNS Settings

Make sure your device is configured correctly:

Windows:

ipconfig /all Look for "DNS Servers" - you should see valid IP addresses.

Mac:

scutil --dns Check the resolver configurations.

Step 3: Flush Your DNS Cache

Old cached records cause lots of problems. Clear them:

Windows:

ipconfig /flushdns

Mac:

sudo dscacheutil -flushcache

Chrome:

Visit chrome://net-internals/#dns

Step 4: Test DNS Resolution

Use nslookup or dig to test:

nslookup google.com dig google.com

If these fail, your DNS server might be down or unreachable.

Step 5: Try Different DNS Servers

Temporarily switch to a public DNS like Cloudflare (1.1.1.1) or Google (8.8.8.8). If that fixes the problem, your original DNS server was the issue.

Common DNS Problems and Solutions

"DNS server not responding"

- Restart your router - Check if your ISP is having issues - Switch to public DNS

"DNS_PROBE_FINISHED_NXDOMAIN"

- The domain doesn't exist or DNS can't find it - Check for typos in the URL - Flush DNS cache - Try different DNS server

Slow DNS resolution

- Switch to faster DNS (Cloudflare is usually quickest) - Check for malware that might be intercepting DNS - Your ISP's DNS might be overloaded

Intermittent DNS failures

- Could be network instability - Try wired connection instead of WiFi - Check router logs for errors

When to Call for Help

If you've tried everything and DNS still isn't working: - Contact your ISP - they might have an outage - Check if the website itself is down (use a service like downdetector) - If it's your own domain, contact your registrar or hosting provider

Most DNS problems are fixable with cache clearing and server switching. The tricky ones usually point to bigger network issues.