# SRV Submissions-TCP DNS Lookup

> SRV Submissions-TCP DNS Lookup is a paid API for AI agents from dns.intel.rallylive.ca, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-10).

Returns SRV DNS records for the _submissions._tcp service of a domain, revealing the priority, weight, port, and target host for the email submissions service.

## Facts

- Endpoint: GET https://dns.intel.rallylive.ca/dns/srv/submissions-tcp?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-10
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/srv-submissions-tcp-dns-lookup-00aef39a
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Sl6O_bnFShV88eyPqWQj1

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 srv-submissions-tcp-dns-lookup-00aef39a
```

Example prompt: Can you look up the _submissions._tcp SRV records for example.com to find out which server and port handle its email submission service?

## When to prefer this

Use this endpoint when you need to programmatically discover the email submission service endpoint (host, port, priority, weight) for a domain using standard SRV DNS records, without manually guessing hostnames or ports. Prefer this over generic DNS A/CNAME lookups when you specifically need service-level routing metadata for SMTP submission (port 587/465 discovery). Ideal for email infrastructure auditing, client configuration automation, or multi-domain delivery orchestration.

## Known failure modes

- Domain does not exist or has no _submissions._tcp SRV record — returns empty result or NXDOMAIN
- Malformed domain name input causes query failure
- Cloudflare DoH upstream timeout or rate limit returns an error
- Domain specified without required 'input' wrapper causes schema validation failure

## How this service works

SUBMISSIONS service discovery (_submissions._tcp.<domain>): SRV records with priority, weight, port and target host, from Cloudflare DoH. Tells a client where the domain's submissions service lives without guessing hosts. $0.01 per lookup.

## Output

A set of SRV DNS records for _submissions._tcp.<domain>, each containing priority (numeric precedence), weight (load balancing factor), port (TCP port the service listens on), and target (FQDN of the host providing the submissions service). Returns an empty or NXDOMAIN-equivalent result if no such record exists.

## 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/srv-submissions-tcp-dns-lookup-00aef39a/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from dns.intel.rallylive.ca](https://www.zero.xyz/host/dns.intel.rallylive.ca/llms.txt)