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To check whether a domain resolves, look it up with a DNS lookup page or run a command such as nslookup example.com on Windows or dig example.com on macOS or Linux. A result applies only to the resolver you asked and the record type you queried, so compare resolvers and specify the record type before deciding a domain is broken.
Run a basic DNS check
A basic lookup asks a DNS resolver for records associated with a domain. For a quick check, use a web lookup page; for more control, use a command-line utility. Google’s Public DNS lookup page lets you enter a domain and select a record type: Google Public DNS lookup. Its comments may point to DNSSEC, nameserver, or delegation issues. [Google Public DNS documentation]
Windows: use nslookup
- Open Command Prompt or PowerShell.
- Run
nslookup example.com. Replaceexample.comwith the domain you want to check. - Read the returned DNS server and address, then the answer section. The command queries DNS directly and does not use the Windows client’s DNS cache. Microsoft documents
nslookupfor Windows 10/11 and Windows Server. [Microsoft nslookup reference]
macOS or Linux: use dig
- Open Terminal.
- Run
dig example.comto request the default query, typically an A record. - Check the status, answer section, and server details near the end of the output. Google’s examples use
digfor resolver comparisons and further diagnostics. [Google Public DNS troubleshooting]
Check the record type you actually need
One lookup does not test every DNS record. Query the type relevant to the problem: A for IPv4 addresses, AAAA for IPv6, MX for mail routing, NS for nameservers, TXT for text-based records, or CAA for certificate-authority restrictions. For example, Google’s documentation shows dig @8.8.8.8 example.com CAA to ask Google Public DNS for CAA records. [Google Public DNS command examples]
The @8.8.8.8 part selects Google’s resolver; without it, dig normally uses the resolver configured on your device or network. A query therefore tells you what that resolver returned for that name and type—not necessarily what every resolver or authoritative server will return.
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Compare resolvers when an answer looks wrong
If a lookup fails or returns an unexpected answer, repeat it through another resolver before changing records. For example, on macOS or Linux, compare a default lookup with dig @8.8.8.8 example.com A and dig @1.1.1.1 example.com A. These ask two public resolvers for the same A record. For a fully qualified name in copied commands, preserve a trailing dot when one is shown, such as example.com.; it makes the name explicit and avoids search-suffix ambiguity. Google’s troubleshooting guidance demonstrates comparisons with other resolvers. [Google Public DNS troubleshooting]
- If one resolver fails while another answers, suspect resolver-specific behavior, network filtering, or caching differences before assuming the domain’s DNS records are wrong.
- If several independent public resolvers fail in a similar way, focus next on the domain’s authoritative nameservers and delegation. Google notes: “When Google Public DNS cannot resolve a domain, it is often due to a problem with that domain or its authoritative name servers.” [Google Public DNS troubleshooting]
Understand common DNS lookup errors
Error messages are clues rather than definitive diagnoses. Microsoft’s nslookup reference describes common responses as follows. [Microsoft nslookup reference]
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| Result | What it indicates | What to check next |
|---|---|---|
| Timed out | The DNS server did not respond within the configured wait and retry period. | Try another resolver and check network access or server availability. |
| No records | The name is valid, but it has no record of the type requested. | Confirm that you queried the intended record type and that the domain owner has published it. |
| Nonexistent domain | The queried name does not exist according to the responding server. | Check spelling, subdomain, and whether the name has been created. |
| Server failure | The DNS server encountered an internal inconsistency or could not complete the query. | Compare resolvers; if failures persist, investigate authoritative DNS and DNSSEC. |
| Refused | The server declined to answer the query. | Try a resolver intended to accept public queries, or check whether the server restricts access. |
If you manage the domain, investigate authoritative DNS
When multiple resolvers fail similarly, move beyond the basic lookup. Check whether the authoritative nameservers are reachable, whether the registrar’s delegation points to the intended servers, and whether DNSSEC validation succeeds. Google’s guidance also recommends DNSViz and DNSSEC Analyzer for DNSSEC diagnostics. [Google Public DNS troubleshooting]
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A stale DS record left at the registrar after a DNS-provider change can prevent validating resolvers from accepting the domain’s DNS data if the corresponding DNSKEY records are missing or inconsistent. This can produce SERVFAIL for validating resolvers even when a non-validating path appears different. Verify the DS and DNSKEY chain rather than removing DNSSEC records blindly.
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Check authoritative-server reliability and response size
Compare answers from the authoritative nameservers themselves. If they disagree, time out, or produce truncated UDP responses that do not succeed after a TCP retry, investigate server configuration and reliability. DNS clients may retry a truncated UDP answer over TCP, so authoritative DNS should support both transports. The diagnostic timing and buffer examples in Google’s guide are context-specific troubleshooting examples, not universal pass/fail thresholds. [Google Public DNS troubleshooting]
Do not use ping to measure DNS lookup speed
ping measures network round-trip response to a host, while traceroute traces a network path; neither measures how long a DNS lookup takes. If the question is resolver latency, use a DNS testing tool or compare timed DNS queries instead. Google’s general troubleshooting guidance explicitly distinguishes these tests from DNS resolution speed. [Google Public DNS troubleshooting]
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DNS over HTTPS and DNSSEC are different
DNS over HTTPS (DoH) encrypts DNS traffic between a stub resolver—the client-side component making a query—and a recursive resolver. DNSSEC validates DNS data so a validating resolver can detect certain invalid or tampered responses. They address different parts of the DNS process and are not substitutes for one another. [Google Public DNS DNS-over-HTTPS documentation]
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