DNS Troubleshooting Guide
DNS problems can make a working internet connection appear broken. A browser may report that a site cannot be reached even though other websites still work. Use the following checks from least disruptive to more advanced.
1. Confirm the exact domain
Check spelling, punctuation, and the top-level domain. Remove unnecessary paths and test the bare hostname. For example, test example.com rather than an entire copied URL.
2. Compare devices and networks
Try another browser or device on the same network. Then test the same site through a different network, such as mobile data. If only one device fails, the problem is likely local. If every device on one network fails, the router or resolver may be involved.
3. Check forward records
Use the Domain to IP tool to check A and AAAA records. No answer may mean the domain is unregistered, the record is missing, authoritative servers are unavailable, or the resolver has not received an update.
4. Clear local cache carefully
Restarting the browser or device may clear temporary issues. On Windows, an administrator can use ipconfig /flushdns. Do not copy unrelated commands from untrusted sources, especially commands that disable security software or download scripts.
5. Restart network equipment
Power-cycle the modem and router only if you are authorized to manage them. Wait for each device to finish reconnecting. Business networks should follow their change process rather than restarting shared equipment without approval.
6. Test another trusted resolver
A device or router can temporarily use a reputable public resolver to determine whether the provider resolver is the cause. Record the original settings before changing anything. Managed work or school devices may prohibit this change.
7. Inspect DNS ownership
Website owners should confirm nameservers, zone records, DNSSEC state, certificate coverage, and hosting configuration. A record can be correct while the web server, firewall, or TLS certificate is still misconfigured.
Avoid dangerous “fixes”
- Do not disable the firewall as a permanent solution.
- Do not run unknown PowerShell, shell, or registry scripts.
- Do not install random “DNS repair” applications.
- Do not expose router administration to the public internet.