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Default MongoDB Read Concerns/Write Concerns![](/docs/v4.4/assets/link.svg)
Read Concern![](/docs/v4.4/assets/link.svg)
Default Read Concern![](/docs/v4.4/assets/link.svg)
The default read concern is as follows:
Operations | Default Read Concern |
---|---|
Reads against primary | Note
|
Reads against secondaries if the reads are associated with causally consistent sessions. | Note
|
Reads against secondaries if the reads are not associated with causally consistent sessions. | Note
|
Specify Read Concern: MongoDB Drivers![](/docs/v4.4/assets/link.svg)
Additional Information![](/docs/v4.4/assets/link.svg)
For more information on the available read concerns, see Read Concern.
Write Concern![](/docs/v4.4/assets/link.svg)
Default Write Concern![](/docs/v4.4/assets/link.svg)
The default write concern is
w: 1
.
Note
With the default write concern, data can be rolled back.
This write concern does not guarantee causal consistency.
Specify Write Concern: MongoDB Drivers![](/docs/v4.4/assets/link.svg)
Additional Information![](/docs/v4.4/assets/link.svg)
For more information on the available write concerns, see Write Concern.
Causally Consistency Guarantees![](/docs/v4.4/assets/link.svg)
With causally consistent client sessions, the client sessions only guarantee causal consistency if:
the associated read operations use
"majority"
read concern, andthe associated write operations use
"majority"
write concern.