---
title: "Lookup subdomains for domain."
method: GET
path: "/api/lookup/{domain}"
tags: ["domain"]
---

# Lookup subdomains for domain.

`GET /api/lookup/{domain}`

Returns an array of subdomains.

The response contains the subdomains only, the domain not included (eg.: `["one", "two", ...]`).

If a FQDN is requested than the domain name will be taken out and used in the lookup (eg.: `/api/lookup/columbus.elmasy.com` will be the same as `/api/lookup/elmasy.com`)

If `Accept` header is set to `text/plain`, this endpoint returns a newline delimetered text of the list (eg.: `one\ntwo\nthree`).

# Note
- The subdomain part will be trimmed (eg.: `/api/lookup/totally.invalid.elmasy.com` will be the same as `/api/lookup/elmasy.com`).
- If `domain` not found, the server saves for later process.
- Only the subdomains are sent in the response to save CPU and RAM on the server side and save bandwith on both client- and server-side.

## Path parameters

- `domain` string, required

## Query parameters

- `days` integer

## Response `200`

success

- string[]

## Other responses

- `400` — Invalid domain or days
- `404` — Domain not found.
- `500` — Internal Server Error.
- `502` — Bad Gateway. Upstream failed.
- `504` — Gateway Timeout. Upstream response takes too long.

---

[API](https://skmtc.net/elmasy-com/apis/columbus-api.md) · [All operations](https://skmtc.net/elmasy-com/apis/columbus-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/elmasy-com/columbus-api/versions/afcfa121a5e2/schema)