Use DNS tools to distinguish authoritative data from cached answers and to record evidence for support.
Applies to: Nameservers and DNS records
DNS tells internet services where to find a website, mail server or other service. Changes can be technically correct yet appear inconsistent for a time because recursive resolvers cache earlier answers until their TTL expires.
Key information
| dig | Detailed DNS query tool available on many Linux and macOS systems and through Windows environments that include it. |
|---|---|
| nslookup | Widely available interactive or command-line DNS query tool. |
| Authoritative query | A query sent directly to a nameserver listed for the domain, bypassing ordinary recursive cache. |
| Recursive query | What a normal device asks its configured resolver; the answer may be cached. |
Before you start
- Confirm that you are authorised to manage the domain and identify its authoritative DNS provider.
- Export or record the complete current DNS zone and previous TTL values before making changes.
- Allow for DNS caching and avoid making unrelated DNS changes during the same maintenance window.
Step-by-step
- Find the authoritative nameservers for the domain, for example with a NS query.
- Query the exact record from each authoritative server: dig @ns.example.net host.example.com A or the equivalent nslookup server syntax.
- Query at least two public recursive resolvers and compare TTLs and answers.
- For delegation problems, use dig +trace where available to follow the path from the DNS root.
- For mail issues, query MX, TXT, DKIM selector and DMARC names separately rather than testing only the root domain.
- Copy commands, output and UTC timestamps into the support ticket, removing unrelated local network information where appropriate.
Confirm the result
- You can state whether the authoritative data is correct and whether a difference is caused by caching or delegation.
Common problems
| Symptom | Likely cause | What to do |
|---|---|---|
| The local result differs from public tools. | The device, router, ISP or VPN resolver has a cached or filtered answer. | Flush only local caches after confirming authoritative data, then test on another network. |
| The command returns a trailing dot or quoted strings. | That is normal DNS presentation format. | Compare the semantic value rather than removing characters blindly from the live zone. |
Important notes
- Do not publish private internal hostnames or customer data from diagnostic output in public forums.
When to contact Tudor Internet
Open a ticket through the Customer Portal when the checks above do not resolve the issue, when an action is unavailable for your service, or when continuing could risk data loss or service interruption. Include the following so the request can be investigated efficiently:
- The full domain name
- The current and intended registrar or nameservers
- Any registry or transfer error shown
- Whether website or email service is currently live
Do not send passwords, private keys, full payment-card details, one-time authentication codes or unredacted identity documents in an ordinary support reply.
Related articles
- DNS propagation and caching
- Diagnose NXDOMAIN and SERVFAIL DNS errors
- Manage DNS records
- Create and troubleshoot A and AAAA records
- Plan a DNS change with minimal downtime
Last reviewed: 2026-07-18.
