---
title: "Run one specific DNS/email-authentication/security check against a domain"
method: POST
path: "/api/v1/dns/check"
tags: ["DNS"]
---

# Run one specific DNS/email-authentication/security check against a domain

`POST /api/v1/dns/check`

## Request

- Base URL: `https://firstsales.io`
- URL: `https://firstsales.io/api/v1/dns/check`
- Auth: none required

Single-check DNS diagnostic tool: pass a `checkType` (spf, dkim, dmarc, mx, general, blacklist, iprep, ptr, tls, bimi, arc, ns, txt, cname, a, aaaa, soa, whois, availability, propagation, authority, dnssec, deliverability, smtp, or port) and get back pass/warn/fail sub-checks plus a 0-100 score. Use `dns/validate` instead if you need SPF+DKIM+DMARC+MX together in one call. Rate limit: 10 requests/minute per IP.

## Request body

- object
  - `domain` string, required: Domain name, or an IPv4 address when checkType is iprep/ptr.
  - `checkType` 'spf' | 'dkim' | 'dmarc' | 'mx' | 'general' | 'blacklist' | 'iprep' | 'ptr' | 'tls' | 'bimi' | 'arc' | 'ns' | 'txt' | 'cname' | 'a' | 'aaaa' | 'soa' | 'whois' | 'availability' | 'propagation' | 'authority' | 'dnssec' | 'deliverability' | 'smtp' | 'port', required
  - `selector` string: Optional DKIM selector (alphanumeric + hyphens, max 63 chars); only used when checkType is dkim.

## Response `200`

Check result for the requested checkType.

- DnsCheckResult: Generic result shape shared by all dns/check checkTypes.
  - `exists` boolean, required
  - `records` string[]
  - `checks` object[]
    - `label` string, required
    - `status` 'pass' | 'warn' | 'fail', required
    - `detail` string, required
  - `score` number
  - `error` string
  - `message` string

## Other responses

- `400`: Invalid request — bad input, missing field, or malformed value.
- `429`: Rate limit exceeded for this endpoint. Wait Retry-After seconds and retry.
- `500`: Unexpected server error.

---

[API](https://skmtc.dev/firstsales/apis/firstsales-public-api.md) · [All operations](https://skmtc.dev/firstsales/apis/firstsales-public-api/llms.txt) · [OpenAPI document](https://skmtc.dev/firstsales/apis/firstsales-public-api/revisions/3856191adf12?raw)