> ## Documentation Index
> Fetch the complete documentation index at: https://e-gurl.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
# DoH JSON Health Check
> Check DNS resolver health using JSON-based DoH APIs (RFC 8427)
# DoH JSON Health Check
DNS-MNS supports checking DNS resolver health using JSON-based DNS over HTTPS (DoH) APIs. This feature implements [RFC 8427](https://tools.ietf.org/html/rfc8427) (JSON-encoded DNS queries) and is particularly useful for users in Iran who need to verify if specific DoH resolvers are accessible.
## What is JSON DoH?
Unlike standard DoH which uses binary DNS messages in the HTTP body (RFC 8484), JSON DoH uses JSON format for DNS queries and responses. This makes it:
* **Easier to debug** - Human-readable JSON format
* **Cross-platform** - Works with any HTTP client
* **Lightweight** - Simple GET requests with query parameters
## Usage
### Interactive Mode
From the main menu:
1. Select `[3] Encrypted DNS`
2. Select `[5] DoH JSON Health Check`
3. Enter the resolver URL (or press Enter for default)
4. Select record type (A, AAAA, MX, TXT)
5. Enter domains to check (comma-separated)
### CLI Mode
```bash theme={null}
# Check a single domain with default resolver
dns-mns doh-health google.com
# Check multiple domains
dns-mns doh-health google.com twitter.com github.com
# Use a custom resolver
dns-mns doh-health --resolver https://dns.google/resolve google.com
# Check IPv6 (AAAA) records
dns-mns doh-health --type AAAA google.com
# Check MX records
dns-mns doh-health --type MX gmail.com
# Output results as JSON
dns-mns doh-health google.com --json
# Disable colors (for piping)
dns-mns doh-health google.com --no-color
```
## Default Resolver
The default resolver is `https://dns.theazizi.ir/dns-query`, which is designed to work well in Iran.
## Record Types
| Type | Value | Description |
| ----- | ----- | -------------- |
| A | 1 | IPv4 address |
| AAAA | 28 | IPv6 address |
| MX | 15 | Mail exchange |
| TXT | 16 | Text record |
| CNAME | 5 | Canonical name |
## Understanding Results
### Successful Query
```
#1 google.com ✅ Working
Type: A
Latency: 45ms
Answers:
• 142.250.185.78 (TTL: 300)
```
### NXDOMAIN (Domain Not Found)
```
#2 nonexistent.invalid ⚠️ Domain not found (NXDOMAIN)
Type: A
Latency: 32ms
```
This means the resolver is working, but the domain doesn't exist.
### Failed Query
```
#3 blocked.com ❌ Failed
Type: A
Latency: 5000ms
Error: request failed: timeout
```
This indicates the resolver is not accessible or blocked.
## JSON Output Format
When using `--json`, the output includes:
```json theme={null}
{
"resolver": "https://dns.theazizi.ir/dns-query",
"type": "A",
"summary": {
"total": 3,
"working": 2,
"failed": 1,
"avg_latency_ms": 38.5
},
"results": [
{
"domain": "google.com",
"record_type": "A",
"works": true,
"latency_ms": 45,
"response": {
"Status": 0,
"Answer": [
{
"name": "google.com",
"type": 1,
"TTL": 300,
"data": "142.250.185.78"
}
]
}
}
]
}
```
## Alternative Resolvers
You can use any RFC 8427-compatible resolver:
| Resolver | URL | Notes |
| ---------- | -------------------------------- | --------------------- |
| Google DNS | `https://dns.google/resolve` | Global, reliable |
| Cloudflare | `https://1.1.1.1/dns-query` | Fast, privacy-focused |
| Quad9 | `https://9.9.9.9:5053/dns-query` | Security-focused |
Many popular DoH resolvers may be blocked in Iran. If the default resolver doesn't work, try using a VPN or finding alternative resolvers.
## Troubleshooting
### "request failed: timeout"
* Check your internet connection
* The resolver may be blocked - try a different one
* Try using a VPN
### "HTTP 403" or "HTTP 451"
* The resolver is accessible but refusing requests
* This may indicate blocking or rate limiting
### Empty answers with Status 0
* The domain exists but the resolver returned no records
* The domain may be blocked at the resolver level
* Try a different resolver
## Use Cases
### Verify Resolver Connectivity
```bash theme={null}
dns-mns doh-health google.com
```
Quick check if the default resolver is working.
### Test Multiple Domains
```bash theme={null}
dns-mns doh-health google.com twitter.com telegram.org
```
Check if commonly blocked domains are accessible through the resolver.
### Compare Resolvers
```bash theme={null}
# Test resolver A
dns-mns doh-health --resolver https://dns.theazizi.ir/dns-query google.com --json
# Test resolver B
dns-mns doh-health --resolver https://dns.google/resolve google.com --json
```
Compare performance and accessibility of different resolvers.
### IPv6 Support Check
```bash theme={null}
dns-mns doh-health --type AAAA google.com cloudflare.com
```
Check if IPv6 resolution is working through the resolver.
## Privacy Considerations
When using a DoH resolver, the resolver operator can see your DNS queries. Choose a resolver with a privacy policy you trust. The default resolver (`dns.theazizi.ir`) is designed for Iranian users but you should review its privacy policy.
## Technical Details
### RFC 8427 Format
The tool sends HTTP GET requests with query parameters:
```
GET /dns-query?name=example.com&type=1 HTTP/1.1
Host: dns.example.com
Accept: application/dns-json
```
### Response Format
```json theme={null}
{
"Status": 0,
"TC": false,
"RD": true,
"RA": true,
"AD": false,
"CD": false,
"Question": [{"name": "example.com", "type": 1}],
"Answer": [{"name": "example.com", "type": 1, "TTL": 300, "data": "93.184.216.34"}]
}
```
### Status Codes
| Code | Name | Meaning |
| ---- | -------- | ------------------- |
| 0 | NOERROR | Success |
| 1 | FORMERR | Format error |
| 2 | SERVFAIL | Server failure |
| 3 | NXDOMAIN | Non-existent domain |
| 5 | REFUSED | Query refused |
## Related Commands
* [`dns-mns test-doh`](./doh-dot) - Test standard DoH/DoT providers
* [`dns-mns proxy`](./fallback-proxy) - Start resilient encrypted DNS proxy
* [`dns-mns verify`](./censorship-check) - Check for DNS poisoning/hijacking