Dns header flags explain

dns-header-flags-explain · version 1.0.0 · Communications · free, no key needed

Explain an RFC 1035 DNS header flags word, with reserved Z as an integer 0 through 7.

Use when you need to: explain dns header flags word · decode rfc 1035 qr opcode and rcode · split a dns flags hex word.

Decide before calling

Read the versioned contract and the supported scope below. Reuse dns-header-flags-explain@1.0.0 when your input, required output and limits match it. Choose another approach for an unsupported operation.

Explain the choice

"I can use dns-header-flags-explain@1.0.0 for explain dns header flags word. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

Supported

• explain dns header flags word
• decode rfc 1035 qr opcode and rcode
• split a dns flags hex word
• what does this dns header flag mean
• read the dns header z field
• interpret query and response flag bits
• הסבר דגלי הכותרת של הודעת די אן אס

Not supported

• split header z into ad and cd bits
• explain the edns do bit or opt ttl
• parse a whole dns message
• decide whether a response is authentic

Behavior

• flags_hex is exactly four lowercase hex digits, the RFC 1035 Section 4.1.1 flags word. Diagram columns are numbered 0 through 15 from the left.
• QR is column 0, opcode is columns 1 through 4 as an integer 0..15, AA TC and RD are columns 5 through 7, RA is column 8, Z is columns 9 through 11 as an integer 0..7, and RCODE is columns 12 through 15 as an integer 0..15.
• Opcode names are only the RFC 1035 assignments: 0 query, 1 iquery, 2 status. Other opcodes are unassigned. RCODE names are 0 no_error, 1 format_error, 2 server_failure, 3 name_error, 4 not_implemented, 5 refused. Values 6 through 15 are unassigned. Later names such as NXDOMAIN, AD and CD are not used.
• The word 0070 sets only the three Z columns and returns z 7. A value outside four hex digits fails: longer input is limit_exceeded, any other shape is invalid_input.
• Disclaimer: format transform only; provides no confidentiality, integrity, or authenticity.

Input

• flags_hex (string, required): min length 4; max length 4; pattern ^[0-9a-f]{4}$

Output

• flags (integer, required): min 0; max 65535
• flags_hex (string, required): min length 4; max length 4; pattern ^[0-9a-f]{4}$
• qr (boolean, required)
• opcode (integer, required): min 0; max 15
• opcode_name (one of "query", "iquery", "status", "unassigned", required)
• aa (boolean, required)
• tc (boolean, required)
• rd (boolean, required)
• ra (boolean, required)
• z (integer, required): min 0; max 7
• rcode (integer, required): min 0; max 15
• rcode_name (one of "no_error", "format_error", "server_failure", "name_error", "not_implemented", "refused", "unassigned", required)

Limits

• max flags hex chars: 4

Example

Request input:

{
  "flags_hex": "0070"
}

Response:

{
  "result": {
    "flags": 112,
    "flags_hex": "0070",
    "qr": false,
    "opcode": 0,
    "opcode_name": "query",
    "aa": false,
    "tc": false,
    "rd": false,
    "ra": false,
    "z": 7,
    "rcode": 0,
    "rcode_name": "no_error"
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "dns-header-flags-explain",
  "version": "1.0.0",
  "input": {
    "flags_hex": "0070"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/dns-header-flags-explain/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"flags_hex":"0070"}'

The machine-readable contract is at /v1/tools/dns-header-flags-explain/versions/1.0.0.

CLI

node cli.mjs run dns-header-flags-explain 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

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