# DNS CNAME Chain Check

> DNS CNAME Chain Check is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Validates a caller-supplied DNS CNAME chain for loops and hop-count budget violations, returning a deterministic pass/advisory verdict without any external DNS lookups.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/dns-cname-chain-check
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/dns-cname-chain-check-64bf550c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_r-O94SBqMPE_QN5TGYHXc

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 dns-cname-chain-check-64bf550c -d '<json body>'
```

Example prompt: Check this CNAME chain for loops and make sure it doesn't exceed 5 hops: ['cdn.example.com', 'lb.example.net', 'edge.cdn.net', 'origin.edge.io'].

## When to prefer this

Choose this endpoint when you need a stateless, deterministic, first-party check of a CNAME chain without issuing live DNS queries or relying on an external resolver. Ideal as a preflight before caching, redirecting, or retrying any caller-supplied DNS chain where loop safety and hop budgets must be verified offline against bounded inputs.

## Known failure modes

- Chain array exceeds 256 items — request rejected
- Individual name strings longer than 8192 characters — rejected
- Malformed JSON input — 400 error
- max_hops not provided or non-integer — validation error
- Payment not included or insufficient — x402 payment required response

## How this service works

DNS Cname Chain Check: DNS Cname Chain Check checks a caller-supplied CNAME chain for loops and hop budget from bounded caller-supplied values without an external provider. Call DNS Cname Chain Check before accepting, caching, redirecting, or retrying a caller-supplied web response. Returns normalized web evidence, the computed finding, and an explicit pass or advisory status for DNS Cname Chain Check as versioned deterministic JSON. Price: $0.001 USDC via x402 on Base. First-party, stateless,…

## Output

Returns versioned deterministic JSON containing normalized web evidence about the chain, the computed finding (e.g. detected loop or hop count exceeded), and an explicit pass or advisory status indicating whether the chain is safe to use.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "names": {
   "type": "array",
   "items": {
    "type": "string",
    "maxLength": 8192
   },
   "maxItems": 256,
   "description": "Names supplied to DNS Cname Chain Check; used only for this bounded calculation and processed in memory without retention."
  },
  "max_hops": {
   "type": "integer",
   "description": "Max Hops supplied to DNS Cname Chain Check; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "hops": 2,
   "loop": false,
   "names": [
    "www.example.com",
    "edge.example.net",
    "origin.example.net"
   ],
   "within_budget": true
  },
  "schema": "delx/util-dns-cname-chain-check/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "5413dc5bf3dab733024514776f9526adadb0c9c3253d4fd4df6f85ea895c49ef",
   "external_calls": 0
  },
  "operation": "web_reliability:dns_cname_chain_check"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/dns-cname-chain-check-64bf550c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.delx.ai](https://www.zero.xyz/host/api.delx.ai/llms.txt)