---
title: Request
summary: API reference for Request.
status: draft
owner: <owner>
last_reviewed: 2026-07-23
library: SAIF.Framework.DNS
reference_type: package
---

# Request

`Request` is the caller-facing message builder for a DNS query. It logically consists of one or more `Question` objects plus header-level flags (`Opcode`, `RecursionDesired`), and serializes itself into an RFC1035 wire-format byte array via `GetMessage()`.

## Purpose
- Accumulate one or more `Question` instances to be sent to a DNS server.
- Serialize the accumulated questions and header flags into a wire-format byte array ready for UDP transmission.

## Context
- Namespace: `SAIF.Framework.DNS`
- Assembly/package: `SAIF.BOF.Framework.DNS`

## Public members
| Member | Signature | Purpose |
| --- | --- | --- |
| RecursionDesired | `public bool RecursionDesired { get; set; }` | Whether the "recursion desired" flag is set in the request header; defaults to `true`. |
| Opcode | `public Opcode Opcode { get; set; }` | The query opcode (RFC1035 4.1.1); defaults to `Opcode.StandardQuery`. |
| Request() | `public Request()` | Constructs a request with default flags (`RecursionDesired = true`, `Opcode = StandardQuery`) and an empty question list. |
| AddQuestion | `public void AddQuestion(Question question)` | Adds a `Question` to the request; throws `ArgumentNullException` if `question` is `null`. |
| GetMessage | `public byte[] GetMessage()` | Serializes the header and all added questions into an RFC1035 wire-format byte array. |

## Behavioral notes
- The first two bytes of the serialized message (the transaction id) are left as zero; `Resolver.UdpTransfer` stamps them with a unique id immediately before sending*.
- `GetMessage()` always writes zero counts for answer, name-server, and additional-record sections, since a request never carries those sections.
- Domain names are encoded label-by-label (length-prefixed) without using the message-compression scheme implemented by `Pointer` for decoding.

## Constraints and usage notes
- Many DNS servers do not support more than one question per request; callers are advised to add only one `Question` per `Request` and to check `Response.ReturnCode` if they do not*.

> **Note:** Statements marked with * were inferred from code structure, naming conventions, or
> contextual evidence where direct confirmation was not available in source artifacts.

## Sources
- SAIF.Framework.DNS\Request.cs