DNS Doctor - DNS & DMARC Tools

Add a domain to the signed-in user's DNS Doctor monitoring and return the ownership-check TXT record they must publish, plus where their DNS is hosted, a provider-specific guide link and, when their provider supports it, a one-click apply URL. Re-adding a domain they already monitor returns that domain rather than an error. Needs a linked DNS Doctor account: until the human has one, or if the host's connect prompt fails, use start_monitoring_signup and print its link instead. Print every record host and value EXACTLY as returned — never rewrite, reformat or improve a record string. Nothing here is applied to anyone's DNS: a human publishes every record, and you must show them what you are about to add and get their approval before using any DNS tool of your own.

Use this when the user asks who can send email as their domain through SPF includes, or wants an SPF supply-chain or third-party sender audit. Audit a domain's SPF supply chain: walks every include and redirect it delegates to, and reports who can transitively send as it. Returns the resolved tree, per-node lookup attribution, the total authorized IPv4 address count, and typed findings — include_broken (a target that no longer publishes SPF, a PermError today), include_registrable (a delegated-to domain that does not exist, so a stranger who registers it becomes an authorized sender), include_expiring (registration lapsing within 30 days), pass_all_nested (a +all deep in the chain) and spf_record_unusable (the audited domain's OWN record is missing or does not parse, so there is no chain to walk). A domain we could not verify is reported as unverified and NEVER as available — never tell anyone a name is free on this tool's say-so unless the finding is include_registrable AND carries registry_confirmed: true. A registry_confirmed: false finding rests on DNS alone, which cannot tell an unsold name from one in redemption or on clientHold: report the mechanism as broken and the takeover risk as possible, but never as an available domain. Findings are risk analysis, not instructions: no SPF fix record exists here or anywhere else in DNS Doctor, because dropping a mechanism can silently de-authorize a real sender — relay the findings and let the domain's owner decide. Use count_spf_lookups instead when the question is only the 10-lookup limit.

Use this when the user asks how to move DMARC on from p=none, whether it is safe to tighten DMARC, or what the next DMARC policy step is for a domain (a scan can justify quarantine at most; reject needs monitoring evidence) — and after any report showing DMARC below enforcement. Return a validated DMARC enforcement-upgrade record for a domain. A scan can justify p=quarantine at MOST: the alignment signal (valid aligned SPF and a DKIM selector) is derived server-side — a caller can never assert it — and p=reject is unlocked only by aggregate-report evidence over a full reporting window (monitoring), never by a scan. `record` is null when there is no honest upgrade to offer (the domain does not exist; the DMARC lookup itself hit NXDOMAIN while the existence probe did not resolve; the DMARC lookup temp-failed; no alignment signal was observed at all, so a non-enforcing domain is told to publish rua= reporting first and an enforcing one is left alone; or the domain already applies a policy at least as strong as this scan justifies): a null record is the ANSWER, not a fault — relay `rationale` and never compose a record to fill the gap. A returned record also carries np=reject (the DMARCbis tag covering non-existent subdomains, which can have no legitimate aligned mail) unless the domain already publishes an np tag, which is preserved as-is. Present a returned record verbatim; a human must approve before publishing.

Use this when the user asks how to protect a domain that sends no email from being spoofed. Build the three-record hardening pack that makes a NON-SENDING domain unusable for spoofing: a Null MX, a hard-fail SPF record, and a p=reject; np=reject DMARC record. For parked, redirect and brand-defensive domains only — NEVER for a domain that sends any mail, including transactional or one legacy system. Do NOT set confirm_no_mail on your own judgment or because a scan looked quiet: only the human who owns the domain can confirm it sends nothing, so ask them first. That flag unlocks the question, not the answer — the server re-checks DNS itself (existence, MX, SPF, DKIM selectors) and returns records: null with a rationale when it finds evidence of mail; relay that rationale rather than retrying. A lookup failure is reported as a failure, never as a pack. Publishing is the human's decision: present the records verbatim, in the order given, and let them approve each one.

Use this when the user asks whether DKIM is set up for a sending platform, whether a specific selector exists, or why DKIM fails. Check ONE specific DKIM selector on a domain — the exact selector the sending platform uses (e.g. `google`, `s1`), which a full scan's common-selector sweep may miss. Returns the verdict, its explanation, and the published key record when one resolves. No fix record is returned: a DKIM key is generated by the sending platform, so the fix is always to publish what that platform gives the owner.

Check whether the ownership TXT record for a domain the user has added is visible yet, and mark it verified when it is. The result says WHICH outcome occurred and which nameservers were asked, so you can tell 'not published yet' from 'published with the wrong value' from 'our lookup did not complete' — a lookup that did not complete is TRANSIENT, never a verdict about their DNS. On success the result also carries the DMARC reporting record that turns monitoring on. Print every record host and value EXACTLY as returned — never rewrite, reformat or improve a record string. Nothing here is applied to anyone's DNS: a human publishes every record, and you must show them what you are about to add and get their approval before using any DNS tool of your own.

Use this when the user asks about lookalike, look-alike, typosquat or impersonation domains of their domain, or whether someone has registered a name close to theirs. DNS-only: checks the closest variants of the name and returns facts — how many resolve and how many accept mail, with up to ten resolving names (each with the kind of variant, whether it accepts mail, and same_infra when it points at the domain's own nameservers or mail servers, which usually means the owner registered it defensively). Never a verdict: relay the names as facts and never call one malicious — resolving only means the name is registered and answers. A name that could not be checked counts as unknown, never as free, and complete is false while any name is unknown. Unregistered names are never listed. next_steps carries the monitoring hand-off (daily watching with alerts and a threat score per name): print its signup_url verbatim as a clickable markdown link on its own line.

Use this when the user asks whether a DNS change has propagated globally, or why a record shows in one place and not another. Check whether a DNS change has propagated GLOBALLY: six vantage points (five owner-run probes across four continents plus this server's own resolver) each read the same name through several resolvers, and the grid plus a deterministic verdict comes back. Call it after the human publishes a record — you have ONE network vantage point, and a record that resolves for you can still be missing elsewhere. `name` is the exact name (www. is not stripped, _dmarc.example.com works), `record_type` is A|AAAA|CNAME|MX|TXT|NS, and the optional `expected_value` turns each cell into match or mismatch instead of agreement-only. Observation only: no record is ever composed here. A cell that did not answer is `unavailable`, which is NOT a negative result, and when fewer than three vantage points were reached the verdict downgrades to `unknown` — report vantage_reached of vantage_total rather than calling a name converged on partial coverage.

Use this when the user asks whether a DNS change has landed, wants a DNS record looked up, or wants to verify a record they just published — or whenever answering needs the live value of a record. Check whether a DNS change has landed: reads the record from the domain's OWN nameservers (cache-free) and from two public caching resolvers, and reports whether they agree. `kind` is one of spf|dmarc|txt|mx|cname|a|aaaa — pass the kind, not a query name: `dmarc` reads TXT at _dmarc.<domain> and `spf` reads apex TXT, each filtered to the matching record. `host` prepends a label (txt, cname, a and aaaa only). Empty values mean the record is genuinely absent. When in_sync is false, max_wait_seconds is the largest remaining cached TTL — the wait before those resolvers refresh. This samples two resolvers, so never describe it as worldwide or as propagation coverage.

Use this when the user asks about reverse DNS, PTR records, or FCrDNS for a mail server IP. Check one sending IP's forward-confirmed reverse DNS (FCrDNS): reads the IP's PTR record, then resolves that hostname back and reports whether it returns to the same IP. `verdict` is confirmed (the pair agrees — what receivers want to see), ptr_missing (the IP publishes no reverse record), or mismatch (a PTR that does not resolve back). A PTR on its own proves nothing, because the IP's operator writes its own reverse zone — only the forward confirmation is evidence, so never report a bare PTR as verified. The fix is always made by whoever controls the IP (the hosting or mail provider), never in the sending domain's own DNS. Pass a public IPv4 or IPv6 address.