DNS Troubleshooting Guide

Symptoms

• • Browser shows "This site can't be reached" or "DNS_PROBE_FINISHED_NXDOMAIN"
• • "Server not found" error
• • Domain name doesn't resolve to an IP address

Solutions

1. 1.Check DNS Records: Verify A or CNAME records exist and point to the correct IP/domain using our DNS checker.
2. 2.Verify Nameservers: Ensure domain is using correct nameservers and they're configured properly.
3. 3.Check Propagation: If you recently changed DNS, wait for propagation (24-48 hours for nameserver changes).
4. 4.Clear DNS Cache: Flush your local DNS cache and try again.
5. 5.Test Different DNS Servers: Try using public DNS (8.8.8.8 or 1.1.1.1) to rule out ISP DNS issues.

Symptoms

• • Websites take a long time to start loading
• • Delay before content appears
• • DNS queries take several seconds

Solutions

1. 1.Use Faster DNS Servers: Switch to public DNS like Cloudflare (1.1.1.1) or Google (8.8.8.8).
2. 2.Check Nameserver Performance: Your authoritative nameservers may be slow - consider using a fast DNS provider.
3. 3.Optimize TTL: Balance TTL values - too low causes more queries, too high delays updates.
4. 4.DNS Caching: Ensure DNS responses are being cached properly at multiple levels.

Symptoms

• • Incoming emails bounce or are rejected
• • "Mail server not found" errors
• • Email clients can't connect to mail server

Solutions

1. 1.Check MX Records: Verify MX records exist and point to correct mail servers using DNS lookup.
2. 2.Verify Priority Values: MX records must have priority values (lower = higher priority).
3. 3.Check A Records for Mail Servers: Mail server hostnames in MX records must resolve to IP addresses.
4. 4.SPF/DKIM/DMARC: Ensure email authentication records (TXT records) are configured correctly.
5. 5.Allow Propagation Time: Wait 24-48 hours after MX record changes for full propagation.

Symptoms

• • DNS changes work in some locations but not others
• • Inconsistent DNS resolution globally
• • Changes take longer than expected to appear

Solutions

1. 1.Check Global Propagation: Use our DNS propagation checker to see status across all regions.
2. 2.Lower TTL Before Changes: Reduce TTL to 300-600 seconds 24-48 hours before making changes.
3. 3.Be Patient: Normal propagation takes 15-60 minutes, nameserver changes can take 24-48 hours.
4. 4.Clear Caches: Flush DNS caches to see changes immediately on your local machine.

Symptoms

• • Email marked as spam
• • DNS spoofing warnings
• • SSL certificate errors

Solutions

1. 1.Enable DNSSEC: Add DNS Security Extensions to prevent DNS spoofing attacks.
2. 2.Configure SPF Records: Add SPF TXT record to authorize sending mail servers.
3. 3.Set Up DKIM: Configure DKIM keys for email authentication.
4. 4.DMARC Policy: Implement DMARC to protect against email spoofing.
5. 5.CAA Records: Add CAA records to control which CAs can issue SSL certificates.