Class DnsQueryOptions

    The options used to override the defaults of LookupClient per query.

    Inheritance
    Object
    DnsQueryOptions
    DnsQueryAndServerOptions
    Inherited Members
    Namespace: DnsClient
    Assembly: DnsClient.dll
    Syntax
    public class DnsQueryOptions

    Fields

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    MaximumBufferSize

    The maximum reasonable payload size.

    Declaration
    public const int MaximumBufferSize = 4096
    Field Value
    Type Description
    Int32
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    MinimumBufferSize

    The minimum payload size. Anything equal or less than that will default back to this value and might disable EDNS.

    Declaration
    public const int MinimumBufferSize = 512
    Field Value
    Type Description
    Int32

    Properties

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    ContinueOnDnsError

    Gets or sets a flag indicating whether to query the next configured NameServers in case the response of the last query returned a DnsResponseCode other than NoError. Default is True.

    Declaration
    public bool ContinueOnDnsError { get; set; }
    Property Value
    Type Description
    Boolean
    Remarks

    If True, lookup client will continue until a server returns a valid result, or, if no NameServers yield a valid result, the last response with the error will be returned. In case no server yields a valid result and ThrowDnsErrors is also enabled, an exception will be thrown containing the error of the last response.

    If True and ThrowDnsErrors is enabled, the exception will be thrown on first encounter without trying any other servers.

    See Also
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    ContinueOnEmptyResponse

    Gets or sets a flag indicating whether to query the next configured NameServers if the response does not have an error DnsResponseCode but the query was not answered by the response. Default is True.

    Declaration
    public bool ContinueOnEmptyResponse { get; set; }
    Property Value
    Type Description
    Boolean
    Remarks

    The query is answered if there is at least one DnsResourceRecord in the answers section matching the DnsQuestion's QueryType.

    If there are zero answers in the response, the query is not answered, independent of the QueryType. If there are answers in the response, the QueryType is used to find a matching record, query types ANY and AXFR will be ignored by this check.

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    EnableAuditTrail

    Gets or sets a flag indicating whether each IDnsQueryResponse will contain a full documentation of the response(s). Default is False.

    Declaration
    public bool EnableAuditTrail { get; set; }
    Property Value
    Type Description
    Boolean
    See Also
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    ExtendedDnsBufferSize

    Gets or sets the maximum buffer used for UDP requests. Defaults to 4096.

    If this value is less or equal to 512 bytes, EDNS might be disabled.

    Declaration
    public int ExtendedDnsBufferSize { get; set; }
    Property Value
    Type Description
    Int32
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    Recursion

    Gets or sets a flag indicating whether DNS queries should instruct the DNS server to do recursive lookups, or not. Default is True.

    Declaration
    public bool Recursion { get; set; }
    Property Value
    Type Description
    Boolean

    The flag indicating if recursion should be used or not.
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    RequestDnsSecRecords

    Gets or sets a flag indicating whether EDNS should be enabled and the DO flag should be set. Defaults to False.

    Declaration
    public bool RequestDnsSecRecords { get; set; }
    Property Value
    Type Description
    Boolean
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    Retries

    Gets or sets the number of tries to get a response from one name server before trying the next one. Only transient errors, like network or connection errors will be retried. Default is 2 which will be three tries total.

    If all configured NameServers error out after retries, an exception will be thrown at the end.

    Declaration
    public int Retries { get; set; }
    Property Value
    Type Description
    Int32

    The number of retries.
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    ThrowDnsErrors

    Gets or sets a flag indicating whether the ILookupClient should throw a DnsResponseException in case the query result has a DnsResponseCode other than NoError. Default is False.

    Declaration
    public bool ThrowDnsErrors { get; set; }
    Property Value
    Type Description
    Boolean
    Remarks

    If set to False, the query will return a result with an ErrorMessage which contains more information.

    If set to True, any query method of IDnsQuery will throw an DnsResponseException if the response header indicates an error.

    If both, ContinueOnDnsError and ThrowDnsErrors are set to True, ILookupClient will continue to query all configured NameServers. If none of the servers yield a valid response, a DnsResponseException will be thrown with the error of the last response.

    See Also
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    Timeout

    Gets or sets the request timeout in milliseconds. Timeout is used for limiting the connection and request time for one operation. Timeout must be greater than zero and less than MaxValue. If InfiniteTimeSpan (or -1) is used, no timeout will be applied. Default is 5 seconds.

    Declaration
    public TimeSpan Timeout { get; set; }
    Property Value
    Type Description
    TimeSpan
    Remarks

    If a very short timeout is configured, queries will more likely result in TimeoutExceptions.

    Important to note, TimeoutExceptions will be retried, if Retries are not disabled (set to 0). This should help in case one or more configured DNS servers are not reachable or under load for example.

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    UseCache

    Gets or sets a flag indicating whether DNS queries should use response caching or not. The cache duration is calculated by the resource record of the response. Usually, the lowest TTL is used. Default is True.

    Declaration
    public bool UseCache { get; set; }
    Property Value
    Type Description
    Boolean
    Remarks

    In case the DNS Server returns records with a TTL of zero. The response cannot be cached.

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    UseRandomNameServer

    Gets or sets a flag indicating whether the ILookupClient can cycle through all configured NameServers on each consecutive request, basically using a random server, or not. Default is True. If only one NameServer is configured, this setting is not used.

    Declaration
    public bool UseRandomNameServer { get; set; }
    Property Value
    Type Description
    Boolean
    Remarks

    If False, configured endpoint will be used in random order. If True, the order will be preserved.

    Even if UseRandomNameServer is set to True, the endpoint might still get disabled and might not being used for some time if it errors out, e.g. no connection can be established.

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    UseTcpFallback

    Gets or sets a flag indicating whether Tcp should be used in case a Udp response is truncated. Default is True.

    If False, truncated results will potentially yield no or incomplete answers.

    Declaration
    public bool UseTcpFallback { get; set; }
    Property Value
    Type Description
    Boolean
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    UseTcpOnly

    Gets or sets a flag indicating whether Udp should not be used at all. Default is False.

    Enable this only if Udp cannot be used because of your firewall rules for example. Also, zone transfers (see AXFR) must use TCP only.

    Declaration
    public bool UseTcpOnly { get; set; }
    Property Value
    Type Description
    Boolean

    Operators

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    Implicit(DnsQueryOptions to DnsQuerySettings)

    Converts the query options into readonly settings.

    Declaration
    public static implicit operator DnsQuerySettings(DnsQueryOptions fromOptions)
    Parameters
    Type Name Description
    DnsQueryOptions fromOptions

    The options.
    Returns
    Type Description
    DnsQuerySettings
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