Enum ResponseCode 

#[non_exhaustive]
pub enum ResponseCode {
    NoError,
    FormErr,
    ServFail,
    NXDomain,
    NotImp,
    Refused,
    YXDomain,
    YXRRSet,
    NXRRSet,
    NotAuth,
    NotZone,
    DSOTYPENI,
    BADVERS,
    BADKEY,
    BADTIME,
    BADMODE,
    BADNAME,
    BADALG,
    BADTRUNC,
    BADCOOKIE,
    Unknown(u8),
}

Available on crate features dns and std only.

A DNS response code (RCODE) from the IANA DNS RCODEs registry.

The message header carries only the low four bits; EDNS(0) and TSIG widen the field by supplying the upper bits, so values above 15 only occur once those extensions have been read. Unassigned and private-use values are retained by ResponseCode::Unknown.

This list reflects a snapshot of the IANA DNS RCODEs registry taken on 2026-09-16, restricted to the values that fit the octet this enum stores. The registry reserves everything up to 65535 for future use.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

NoError

Reports that no error occurred.

FormErr

Reports that the server could not interpret the query.

ServFail

Reports a failure that prevented the server from answering.

NXDomain

Reports that the queried name does not exist.

NotImp

Reports that the server does not implement the requested query.

Refused

Reports that policy prevented the server from answering.

YXDomain

Reports that a name exists that the update required to be absent.

YXRRSet

Reports that an RRset exists that the update required to be absent.

NXRRSet

Reports that an RRset the update required to be present is absent.

NotAuth

Reports an unauthorized update, or a server not authoritative for the zone.

NotZone

Reports a name outside the zone named in the update.

DSOTYPENI

Reports a DSO-TYPE that the server does not implement.

BADVERS

Reports an unsupported EDNS version, and a bad TSIG signature.

The registry assigns this value twice: BADVERS for EDNS and BADSIG for TSIG. Which one applies follows from the extension that carried the code.

BADKEY

Reports a key not recognized by the server.

BADTIME

Reports a signature outside its validity window.

BADMODE

Reports a bad TKEY mode.

BADNAME

Reports a duplicate key name.

BADALG

Reports an algorithm that the server does not support.

BADTRUNC

Reports a truncated TSIG message authentication code.

BADCOOKIE

Reports a bad or missing server cookie.

Unknown(u8)

Retains an unrecognized numeric value.

Implementations

impl ResponseCode

pub fn variant_name(&self) -> Cow<'static, str>

Return this value’s variant name, or its decimal number when the value is unknown.

Known values borrow their 'static mnemonic, and Self::Unknown values render their numeric value. Unlike Display and Debug the result is a bare, stable label, suitable for log fields, metrics, and telemetry.

Trait Implementations

impl Clone for ResponseCode

fn clone(&self) -> ResponseCode

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for ResponseCode

impl Debug for ResponseCode

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for ResponseCode

fn deserialize<D>( deserializer: D, ) -> Result<ResponseCode, <D as Deserializer<'de>>::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for ResponseCode

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Eq for ResponseCode

impl From<ResponseCode> for u8

fn from(value: ResponseCode) -> u8

Converts to this type from the input type.

impl From<u8> for ResponseCode

fn from(x: u8) -> ResponseCode

Converts to this type from the input type.

impl Hash for ResponseCode

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl LowerHex for ResponseCode

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Ord for ResponseCode

fn cmp(&self, other: &ResponseCode) -> Ordering

Compare by numeric value, then distinguish colliding variants.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

fn clamp_to<R>(self, range: R) -> Self

where Self: Sized, R: ClampBounds<Self>,

🔬This is a nightly-only experimental API. (clamp_to)

Restrict a value to a certain range.

impl PartialEq for ResponseCode

fn eq(&self, other: &ResponseCode) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialOrd for ResponseCode

fn partial_cmp(&self, other: &ResponseCode) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Serialize for ResponseCode

fn serialize<S>( &self, serializer: S, ) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for ResponseCode

impl UpperHex for ResponseCode

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.