DNS resolution issues-causes and troubleshooting

DNS resolution is the process that translates domain names (example.com) into IP addresses (192.0.2.1) so browsers can find your server. When DNS resolution fails, browsers can't reach your site and show "Server not found" or similar errors.

Common DNS resolution errors

• "Server not found" - DNS didn't resolve the domain to an IP address
• "Host not found" - Same as above, slightly different error message
• "Domain not available" - Domain registration expired or nameservers are wrong
• "This site can't be reached" - DNS resolved, but the website isn't responding
• "DNS server refused connection" - DNS server is blocking the query

DNS propagation delays

The most common reason for DNS resolution issues is propagation delay.

When you change nameservers (pointing your domain to UnderHost), the change doesn't take effect instantly worldwide. DNS propagation takes time:

• Typical: 1-4 hours for most users
• In rare cases: Up to 24-48 hours
• Why? Every internet service provider (ISP) and DNS resolver caches nameserver information. When you change nameservers, all these cached entries expire and are refreshed gradually

How to check propagation status:

See DNS propagation explained for methods to check your domain name propagation status. Multiple DNS services worldwide can help you see which regions have propagated and which have not.

If propagation shows green but your domain still isn't loading: Clear your browser cache (Ctrl+Shift+Delete), flush your local DNS cache (see below), or wait a few more hours.

Nameserver issues

Check what nameservers your domain is using

1. Use a public Whois lookup like ICANN Whois or Whois.net
2. Enter your domain
3. Look for "Nameservers" section
4. You should see UnderHost nameservers:
   • Canada Shared Hosting: ns01.underhost.com and ns02.underhost.com
   • Offshore Hosting: dns1.underhost.com and dns2.underhost.com
   • Cloud VPS: Check your welcome email (varies by location)

If your domain is pointing to the wrong nameservers:

1. Log in to your domain registrar (GoDaddy, Namecheap, Google Domains, etc.)
2. Find "Nameservers" or "DNS Settings"
3. Replace with UnderHost nameservers
4. Save changes
5. Wait for propagation (1-24 hours)

Local DNS cache problems

Your computer and browser cache DNS lookups for speed. If you recently changed nameservers but your local cache still has the old information, you'll see the old (or no) result.

Clear DNS cache on Windows

ipconfig /flushdns

Open Command Prompt and run the above command.

Clear DNS cache on macOS

sudo dscacheutil -flushcache

Open Terminal and run the above command.

Clear browser cache

Press Ctrl+Shift+Delete (Windows) or Cmd+Shift+Delete (Mac) to open browser cache clearing options. Clear "Cache" and/or "Cookies".

DNS diagnostic tools

nslookup command (Windows)

nslookup example.com

Returns the IP address for your domain. Should show UnderHost's IP address.

dig command (macOS/Linux)

dig example.com

Similar to nslookup. Shows DNS lookup details including nameserver, IP address, and record type.

DNS Check Tool

Use UnderHost DNS Check Tool to verify all your DNS records (A, CNAME, MX, TXT, NS).

Troubleshooting checklist

In order of likelihood:

• ☐ Wait for propagation: It's been less than 4 hours since nameserver change? Wait and try again.
• ☐ Clear local DNS cache: Run ipconfig /flushdns (Windows) or dscacheutil -flushcache (Mac)
• ☐ Clear browser cache: Ctrl+Shift+Delete and clear cache
• ☐ Check propagation status: Use propagation checker tool to verify nameservers are active
• ☐ Verify nameservers: Use Whois Lookup to confirm domain is pointing to UnderHost nameservers
• ☐ Check DNS records: Use DNS Check tool to verify A record points to correct IP
• ☐ Try different DNS resolver: Change your computer's DNS to 8.8.8.8 (Google) or 1.1.1.1 (Cloudflare) to test
• ☐ Try from different network: Connect via mobile hotspot or different WiFi to rule out ISP issues
• ☐ Check domain expiration: Use Whois Lookup - if domain is expired, renew it at your registrar

Related: Nameservers | Domain propagation | Configure DNS

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