---
title: "Diagnose inbound DNS for a domain"
method: POST
path: "/v1/domains/{domain}/diagnose"
tags: ["Domains"]
---

# Diagnose inbound DNS for a domain

`POST /v1/domains/{domain}/diagnose`

Runs live DNS checks for inbound email readiness (MX correctness, apex CNAME collision, and common DNS blocklists for the Novu mail host). Returns structured issues with plain-language fixes.

## Path parameters

- `domain` string, required

## Response `200`

OK

- DiagnoseDomainResponseDto
  - `ok` boolean, required — True when there are no error-severity issues
  - `runAt` string, required — ISO timestamp when the diagnostic run finished
  - `checks` DomainDiagnosticCheckDto[], required
    - `code` 'mx_missing' | 'mx_wrong_target' | 'mx_low_priority' | 'apex_cname_collision' | 'dnsbl_listed', required
    - `status` 'pass' | 'fail' | 'skipped', required
    - `latencyMs` number, required — Round-trip time for this check in milliseconds
  - `issues` DomainDiagnosticIssueDto[], required
    - `code` 'mx_missing' | 'mx_wrong_target' | 'mx_low_priority' | 'apex_cname_collision' | 'dnsbl_listed', required
    - `severity` 'warn' | 'error', required
    - `message` string, required
    - `fix` string, required — Plain-language remediation guidance

## Other responses

- `400` — Bad Request
- `401` — Unauthorized
- `403` — Forbidden
- `404` — Not Found
- `405` — Method Not Allowed
- `409` — Conflict
- `413` — Payload Too Large
- `414` — URI Too Long
- `415` — Unsupported Media Type
- `422` — Unprocessable Entity
- `429` — The client has sent too many requests in a given amount of time.
- `500` — Internal Server Error
- `503` — The server is currently unable to handle the request due to a temporary overload or scheduled maintenance, which will likely be alleviated after some delay.

---

[API](https://skmtc.net/novu/apis/deprecated-novu-api-use-openapi-json-yaml-instead.md) · [All operations](https://skmtc.net/novu/apis/deprecated-novu-api-use-openapi-json-yaml-instead/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/novu/deprecated-novu-api-use-openapi-json-yaml-instead/revisions/d7137c47680a/schema)