# Data Availability

### Data Availability

Data availability (DA) guarantees that all transaction data necessary for state reconstruction and verification remains accessible to the verifier network. Unlike validium-based designs, Via Network is a **sovereign chain** anchored to **Bitcoin** ensuring final data integrity and censorship resistance.

#### Data Publication and Access

* **Primary DA Layer:** All rollup data is published to **Celestia**, which serves as the primary data availability layer.
* **Retention Period:** Data remains retrievable on Celestia for **30 days**.
* **Verifier Access:** The **verifier network** accesses Celestia data to validate rollup execution off-chain.
* **Fallback Mechanism:** If Celestia data expires or becomes unavailable, verifiers can fetch the missing data from **external archival nodes** within the network.
* **Final Anchoring:** Periodic **state commitments** and **DA proofs** are **anchored on Bitcoin**, providing the ultimate layer of security and auditability.

For a detailed explanation of the original zkStack data availability design, refer to the [zkSync Data Availability documentation](https://docs.zksync.io/zksync-protocol/rollup/data-availability)