What this page covers
Interpret the response code with the queried name, server and time—not from a browser error alone.
Step-by-step workflow
- Repeat the query against the configured resolver.
- Check the exact hostname and search suffix.
- Compare an authoritative or documented alternate resolver only for diagnosis.
- Keep the output private if it contains internal names.
Decision table
| Check | What it tells you | Safe next action |
|---|---|---|
| NXDOMAIN | The queried name was reported as nonexistent | Check spelling and DNS zone |
| SERVFAIL | Resolver could not complete the query | Inspect upstream/validation path |
| Timeout | No timely response was received | Check firewall, path and server load |
Limits and verification
A single response cannot prove an outage or attack. DNS records and caches change over time.
Official sources
- Microsoft — Troubleshoot DNS server issues (DNS diagnosis)
- IETF RFC 2131 — Dynamic Host Configuration Protocol (DHCP message and lease concepts)
Related Router Portal guides
Router login troubleshooting · Router security guide
Keep in mind: Firmware, operating-system menus, ISP policies and regional radio rules can change. Confirm the current official source and exact device before applying a setting.
Our networking steps are lab-tested against standard RFC 1918 private networking protocols across Windows 11 (24H2), macOS Sequoia (15.1), iOS 18, and Android 15. We verify physical device labels and firmware release documentation before publishing gateway instructions. Router Portal is strictly read-only and never requests, intercepts, or logs router passwords.