# is-port-53-open

> is-port-53-open is a paid API for AI agents from ip.intel.rallylive.ca, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-13).

Checks whether TCP port 53 (DNS) is open, closed, or filtered on a given host by attempting a connection from Cloudflare's edge network.

## Facts

- Endpoint: GET https://ip.intel.rallylive.ca/ip/port/53?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/is-port-53-open-7fd63dd4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_yf3gYafOtrtwXfjewo-UI

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability is-port-53-open-7fd63dd4
```

Example prompt: Can you check whether TCP port 53 (DNS) is open on 203.0.113.45? I want to know if that host is exposing its DNS service to the internet without me having to run a scanner.

## When to prefer this

Use this endpoint when you need a quick, external-perspective check of whether TCP port 53 (DNS) is reachable on a specific host without deploying your own scanner. It is particularly useful for security audits, infrastructure validation, and incident response where you want to detect DNS exposure from the public internet. Prefer this over general port scanners when you specifically need DNS port visibility with Cloudflare-edge sourcing and a known per-check cost.

## Known failure modes

- Cloudflare-fronted hosts return inconclusive result because Cloudflare's edge terminates connections
- Host or IP unreachable results in filtered/closed status which may be ambiguous
- Invalid or non-resolvable hostname causes request failure
- Rate limiting or payment failure returns error without port status

## How this service works

Is TCP port 53 (DNS) open on a host? Attempts a connection from Cloudflare's edge and reports open/closed/filtered with the connect time; Cloudflare-fronted hosts are reported as inconclusive because their edge answers for them. Exposure checks for DNS without running a scanner. $0.01 per check.

## Output

Returns the port status (open, closed, or filtered) for TCP port 53 on the target host, the connection time in milliseconds, and a flag indicating if the result is inconclusive because the host is fronted by Cloudflare's edge (which answers on the host's behalf).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/is-port-53-open-7fd63dd4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from ip.intel.rallylive.ca](https://www.zero.xyz/host/ip.intel.rallylive.ca/llms.txt)