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Connection Options

This section describes the MongoDB connection and authentication options available in the .NET/C# Driver. You can configure your connection using either the connection URI or a MongoClientSettings object.

Using the Connection URI

If you pass a connection URI to the MongoClient constructor, you can include connection options in the string as <name>=<value> pairs. In the following example, the connection URI contains the connectTimeoutMS option with a value of 60000 and the tls option with a value of true:

using MongoDB.Driver;
// Sets the connection URI
const string connectionUri = "mongodb+srv://sample.host:27017/?connectTimeoutMS=60000&tls=true";
// Creates a new client and connects to the server
var client = new MongoClient(connectionUri);

Using `MongoClientSettings`

You can use a MongoClientSettings object to configure connection settings in code rather than in a connection URI. Configuring the connection this way makes it easier to change settings at runtime, helps you catch errors during compilation, and provides more configuration options than the connection URI.

To use a MongoClientSettings object, create an instance of the class, set its properties, and pass it as an argument to the MongoClient constructor:

//const string connectionUri = "mongodb+srv://sample.host:27017/?connectTimeoutMS=60000&tls=true";
// Creates a MongoClientSettings object
var settings = new MongoClientSettings()
{
    Scheme = ConnectionStringScheme.MongoDBPlusSrv,
    Server = new MongoServerAddress("sample.host", 27017),
    ConnectTimeout = new TimeSpan(0, 0, 60),
    UseTls = true
};
// Creates a new client and connects to the server
var client = new MongoClient(settings);

Connection Options

The following table lists each connection option available in the MongoClientSettings class and, if possible, how to achieve the same result in the connection string. If a MongoClientSettings property maps to more than one option in the connection string, the Connection URI Example shows all relevant options.

Note

If you're using a query parameter for a time duration, the value must be in milliseconds. For example, to specify 60 seconds, use the value 60000. If you're using a MongoClientSettings object for a time duration, use the appropriate TimeSpan value.

MongoClientSettings Property

Description

AllowInsecureTls

Specifies whether to relax TLS constraints as much as possible. This can include
allowing invalid certificates or hostname mismatches.

If this property is set to true and SslSettings.CheckCertificateRevocation
is set to false, the .NET/C# Driver will throw an exception.

Data Type: boolean
Default: false
Connection URI Example: tlsInsecure=true

ApplicationName

The app name the driver passes to the server in the client metadata as part of
the connection handshake. The server prints this value to the MongoDB logs once
the connection is established. The value is also recorded in the slow query logs
and profile collections.

Data Type: string
Default: null
Connection URI Example: appName=yourApp

AutoEncryptionOptions

Settings for automatic client-side encryption.

Data Type: AutoEncryptionOptions
Default: null
Connection URI Example: N/A

ClusterConfigurator

Low-level configuration options for sockets, TLS, cluster, and others.

Data Type: Action<ClusterBuilder>
Default: null
Connection URI Example: N/A

Compressors

The preferred compression types, in order, for wire-protocol messages sent to
or received from the server. The driver uses the first of these compression types
that the server supports.

Data Type: CompressorConfiguration
Default: null
Connection URI Example: compressors=snappy,zstd

ConnectTimeout

The length of time the driver tries to establish a single TCP socket connection
to the server before timing out.

DataType: TimeSpan
Default: 30 seconds
Connection URI Example: connectTimeoutMS=0

Credential

Settings for how the driver authenticates to the server. This includes
authentication credentials, mechanism, source, and other settings.

If you don't specify an authentication mechanism, the driver uses either
SCRAM-SHA-1 or SCRAM-SHA-256, depending on the server version. See
authentication mechanisms for available
authentication mechanisms.

Data Type: MongoCredential
Default: null
Connection URI Example:

mongodb://user1:password1&authMechanism=GSSAPI
&authMechanismProperties=SERVICE_NAME:other,REALM:otherrealm
&authSource=$external

DirectConnection

Specifies whether to force dispatch all operations to the host.

If you specify this option, the driver doesn't accept the
DNS seed list connection format.
You must use the standard connection URI format
instead.

This property must be set to false if you specify more than one
host name.

Data Type: boolean
Default: false
Connection URI Example: directConnection=true

HeartbeatInterval

The interval between regular server-monitoring checks. Must be greater than or
equal to 500 milliseconds.

Data Type: TimeSpan
Default: 10 seconds
Connection URI Example: heartbeatFrequencyMS=5000

HeartbeatTimeout

The length of time a monitoring socket can be idle before timing out.

Data Type: TimeSpan
Default: Same value as ConnectTimeout
Connection URI Example: heartbeatTimeoutMS=5000

IPv6

Specifies whether the host address is in IPv6 format.

Data Type: boolean
Default: false
Connection URI Example: ipv6=true

IsFrozen

Indicates whether the settings have been frozen. Frozen settings can't be changed.
This option is read-only.

Data Type: boolean
Default: false
Connection URI Example: N/A

LinqProvider

The LINQ provider to use.

Data Type: LinqProvider
Default: LinqProvider.V3
Connection URI Example: N/A

LoadBalanced

Specifies whether the driver is connecting to a load balancer. You can set this
property to true only if:

You specify just one host name.
You're not connecting to a replica set.
You're not using the SrvMaxHosts property.
You're not using the DirectConnection property.

Data Type: boolean
Default: false
Connection URI Example: loadBalanced=true

LocalThreshold

The latency window for server eligibility. If a server's round trip takes longer
than the fastest server's round-trip time plus this value, the server isn't
eligible for selection.

Data Type: TimeSpan
Default: 15 milliseconds
Connection URI Example: localThresholdMS=0

LoggingSettings

The settings used for logging.

Data Type: LoggingSettings
Default: null
Connection URI Example: N/A

MaxConnecting

The greatest number of connections a driver's connection pool may be
establishing concurrently.

Data Type: integer
Default: 2
Connection URI Example: maxConnecting=3

MaxConnectionIdleTime

The length of time a connection can be idle before the driver closes it.

Data Type: TimeSpan
Default: 10 minutes
Connection URI Example: maxIdleTimeMS=300000

MaxConnectionLifeTime

The length of time a connection can be pooled before expiring.

Data Type: TimeSpan
Default: 30 minutes
Connection URI Example: maxLifetimeMS=50000

MaxConnectionPoolSize

The greatest number of clients or connections the driver can create in its
connection pool. This count includes connections in use.

Data Type: integer
Default: 100
Connection URI Example: maxPoolSize=150

MinConnectionPoolSize

The number of connections the driver should create and keep in the connection
pool even when no operations are occurring. This count includes connections
in use.

Data Type: integer
Default: 0
Connection URI Example: minPoolSize=1

ReadConcern

The client's default read concern.
See read concern for more information.

Data Type: ReadConcern
Default: ReadConcern.Default
Connection URI Example: readConcernLevel=local

ReadEncoding

The UTF-8 encoding to use for string deserialization.
Strict encoding will throw an exception when an invalid UTF-8 byte sequence
is encountered.

Data Type: UTF8Encoding
Default: Strict encoding
Connection URI Example: N/A

ReadPreference

The client's default read-preference settings. MaxStaleness represents the
longest replication lag, in wall-clock time, that a secondary can experience and
still be eligible for server selection. Specifying -1 means no maximum.
See read preference for more information.

Data Type: ReadPreference
Default: ReadPreference.Primary
Connection URI Example:

readPreference=primaryPreferred
&maxStalenessSeconds=90
&readPreferenceTags=dc:ny,rack:1

You can include the readPreferenceTags parameter in the connection URI more than once. If you do, the client treats each instance as a separate tag set. The order of the tags in the URI determines the order for read preference. You can use this parameter only if the read-preference mode is not primary.

ReplicaSetName

The name of the replica set to connect to.

Data Type: string
Default: null
Connection URI Example: replicaSet=yourReplicaSet

RetryReads

Enables retryable reads.

Data Type: boolean
Default: true
Connection URI Example: retryReads=false

RetryWrites

Enables retryable writes.

Data Type: boolean
Default: true
Connection URI Example: retryWrites=false

Scheme

Specifies whether to use the standard connection string format (MongoDB)
or the DNS seed list format (MongoDBPlusSrv).
See the MongoDB Manual for more
information about connection string formats.

If the DirectConnection property is set to true and you
try to use the DNS seed list format, the .NET/C# Driver will throw an
exception.

Data Type: ConnectionStringScheme
Default: ConnectionStringScheme.MongoDB
Connection URI Example: mongodb+srv://

Server

The host and port number where MongoDB is running.

Data Type: MongoServerAddress
Default: localhost:27017
Connection URI Example: mongodb://sample.host:27017

ServerApi

Allows opting into Stable API versioning. See
the MongoDB Manual for more information about
Stable API versioning.

Data Type: ServerApi
Default: null
Connection URI Example: N/A

ServerMonitoringMode

Specifies the server monitoring protocol to use. When
this option is set to Auto, the monitoring mode is determined
by the environment in which the driver is running. The driver
uses polling mode in function-as-a-service (FaaS) environments,
such as AWS Lambda, and the streaming mode in other environments.

Data Type: ServerMonitoringMode
Default: Auto
Connection URI Example: serverMonitoringMode=poll

Servers

The cluster members where MongoDB is running.

Data Type: IEnumerable<MongoServerAddress>
Default: localhost:27017
Connection URI Example: mongodb://sample.host1:27017,sample.host2:27017

ServerSelectionTimeout

The length of time the driver tries to select a server before timing out.

Data Type: TimeSpan
Default: 30 seconds
Connection URI Example: serverSelectionTimeoutMS=15000

SocketTimeout

The length of time the driver tries to send or receive on a socket before
timing out.

Data Type: TimeSpan
Default: OS default
Connection URI Example: socketTimeoutMS=0

SrvMaxHosts

The greatest number of SRV results to randomly select when initially populating
the seedlist or, during SRV polling, adding new hosts to the topology.

You can use this property only if the connection-string scheme is set
to ConnectionStringScheme.MongoDBPlusSrv. You cannot use it when connecting
to a replica set.

Data Type: integer
Default: 0
Connection URI Example: srvMaxHosts=3

SrvServiceName

The service name of the SRV resource records
that the driver retrieves to construct your seedlist. This
property overrides the default service name for SRV lookup in
discovery and polling.

You can use this property only if the connection-string scheme is set
to ConnectionStringScheme.MongoDBPlusSrv. You cannot use it when connecting
to a replica set.

Data Type: string
Default: "mongodb"
Connection URI Example: srvServiceName="customname"

SslSettings

TLS/SSL options, including client certificates, revocation handling, and
enabled and disabled TLS/SSL protocols.

If SslSettings.CheckCertificateRevocation is set to false and
AllowInsecureTls is set to true, the .NET/C# Driver will throw
an exception.

Data Type: SslSettings
Default: null
Connection URI Example: tlsDisableCertificateRevocationCheck=false

UseTls

Specifies whether to require TLS for connections to the server. If you use
a scheme of "mongodb+srv" or specify other TLS options,
this option defaults to true.

Data Type: boolean
Default: false
Connection URI Example: tls=true

WaitQueueTimeout

The length of time the driver tries to check out a connection from a
server's connection pool before timing out.

Data Type: TimeSpan
Default: 2 minutes
Connection URI Example: waitQueueTimeoutMS=0

WriteConcern

The default write-concern settings, including write timeout and
journaling, for the client.
See write concern for more information.

Data Type: WriteConcern
Default: WriteConcern.Acknowledged
Connection URI Example: w=majority&wTimeoutMS=0&journal=true

WriteEncoding

Specifies whether UTF-8 string serialization is strict or lenient. With strict
encoding, the driver will throw an exception when it encounters an invalid
UTF-8 byte sequence.

Data Type: UTF8Encoding
Default: Strict encoding
Connection URI Example: N/A

Back

Connection Guide

Configure TLS

Connection Options

Using the Connection URI

Using MongoClientSettings

Connection Options

Note

Using `MongoClientSettings`