> For the complete documentation index, see [llms.txt](https://learn.sitecove.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://learn.sitecove.com/how-to-guides/web-hosting/troubleshooting-and-error-fixes/how-to-check-and-fix-dns-issues.md). # How to Check & Fix DNS Issues Domain Name System (DNS) issues can cause websites to become inaccessible, disrupt email services, or slow down browsing. DNS is responsible for translating domain names (e.g., `example.com`) into IP addresses that computers use to identify servers. If DNS fails, users may experience errors such as "DNS Server Not Found" or "DNS\_PROBE\_FINISHED\_NXDOMAIN." This guide covers how to check and fix DNS issues effectively. *** #### **1. How to Check for DNS Issues** Before fixing DNS issues, determine the source of the problem using the following methods: #### **1.1 Use Command Line Tools** **Check DNS Resolution with nslookup** Run the following command in the terminal (Windows, Mac, Linux) to check if the domain resolves correctly: ```bash nslookup example.com ``` If the response does not return an IP address, the DNS server may be down or misconfigured. **Test with Ping** To check connectivity to the server: ```bash ping example.com ``` If the ping fails but resolves an IP address, the issue may be with the website’s server rather than DNS. **Use dig (Linux/Mac)** To query DNS records: ```bash dig example.com ``` This will display the DNS response from the queried server, helping diagnose propagation issues. #### **1.2 Check DNS Status with Online Tools** * [Google Dig Tool](https://toolbox.googleapps.com/apps/dig/) * [DNS Checker](https://www.whatsmydns.net/) * [MXToolBox](https://mxtoolbox.com/) These tools help verify DNS records across different locations. #### **1.3 Flush DNS Cache** Cached DNS records may cause incorrect or outdated resolutions. To clear the cache: * **Windows**: ```bash ipconfig /flushdns ``` * **Mac**: ```bash sudo killall -HUP mDNSResponder ``` * **Linux**: ```bash sudo systemd-resolve --flush-caches ``` *** #### **2. How to Fix DNS Issues** If DNS issues persist, try the following solutions. #### **2.1 Restart Your Router and Modem** A simple router reboot can resolve network-related DNS issues. Turn off the modem and router, wait 10 seconds, then turn them back on. #### **2.2 Change DNS Servers** If your ISP’s DNS is slow or unreliable, switch to a public DNS provider: * **Google DNS**: `8.8.8.8` and `8.8.4.4` * **Cloudflare DNS**: `1.1.1.1` and `1.0.0.1` * **OpenDNS**: `208.67.222.222` and `208.67.220.220` **Windows:** 1. Open **Control Panel > Network and Internet > Network and Sharing Center**. 2. Click **Change adapter settings**. 3. Right-click your network 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 new DNS addresses. 6. Click **OK** and restart your connection. **Mac:** 1. Open **System Preferences > Network**. 2. Select your connection and click **Advanced**. 3. Go to the **DNS** tab and add the new DNS servers. 4. Click **OK** and **Apply**. #### **2.3 Check Your Hosts File** A misconfigured hosts file can override DNS settings. **Windows:** 1. Open Notepad as an administrator. 2. Navigate to `C:\Windows\System32\drivers\etc\hosts`. 3. Ensure no incorrect entries are redirecting domains. **Mac/Linux:** 1. Open Terminal and run: ```bash sudo nano /etc/hosts ``` 2. Remove incorrect entries and save the file. #### **2.4 Check Firewall and Security Software** Firewalls and antivirus programs can block DNS queries. Temporarily disable security software to see if it resolves the issue. #### **2.5 Check Domain’s DNS Records** If you're troubleshooting a website’s DNS, check its DNS records: * **A Record**: Maps the domain to an IP address. * **CNAME Record**: Alias for another domain. * **MX Record**: Defines mail servers for email delivery. Use an online DNS lookup tool or your hosting provider’s DNS management panel to verify these settings. #### **2.6 Restart DNS Services (Advanced Users)** On Windows, restart the DNS client service: ```bash net stop dnscache net start dnscache ``` On Linux: ```bash sudo systemctl restart systemd-resolved ``` #### **2.7 Check for DNS Propagation Delays** If you’ve recently changed DNS records, propagation can take up to 48 hours. Use [WhatsMyDNS](https://www.whatsmydns.net/) to check global propagation. *** #### **3. When to Contact Your ISP or Hosting Provider** If none of the above solutions work: * Contact your **Internet Service Provider (ISP)** if all websites fail to resolve. * Contact your **domain registrar or hosting provider** if only your website is affected. *** #### **Conclusion** DNS issues can be frustrating, but with systematic troubleshooting, they can be identified and resolved. Start by checking DNS resolution, clearing cache, and switching to reliable DNS servers. If problems persist, verify DNS records, inspect firewall settings, and check for misconfigurations. Following these steps will help ensure a smooth and reliable browsing experience. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. 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