# Offset Rewind Protection

{% hint style="warning" %}
In order for the consumer offset mapping functionality to work, both of the following requirements must be met:

* K2K must be configured to publish offset mappings.
* The `k2k-offset-mapping` application must be configured and deployed.

Without both components active, consumer group offsets on the target cluster will not be translated.
{% endhint %}

The K2K Offset Mapping ensures that a committed offset translation is never overwritten by a decision based on stale or older mappings. This can happen for instance when an instance is starting up and hasn't read the whole offset mapping information or when a zombie instance exists.\
\
This guarantee is enforced by storing versioning metadata alongside each consumer group offset commit, using the Kafka consumer group metadata field. Before applying a new offset, the application checks this metadata to confirm that the new mapping is more recent than the one previously applied.

The prefix used for the metadata entries is also configurable.

{% hint style="danger" %}
This safety mechanism can be disabled, but doing so is only recommended for troubleshooting or when performing a full offset reset. 

Disabling it in normal operation may cause committed offsets to regress to an earlier position.
{% endhint %}

```yaml
features:
  applyMappingsGuard: "enabled"
groups:
  offsetGuardPrefix: "k2k_"
```


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