# FAQ Arbitrum

## Arbitrum Documentation/FAQ

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<summary><strong>What is Arbitrum?</strong></summary>

Arbitrum is a Layer 2 and Layer 3 scaling solution on Ethereum designed to make dApps faster and cost-effective, by offloading computation and storage from the Ethereum main chain. Providing higher throughput and lower fees.

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<summary><strong>Arbitrum Chains Ecosystem</strong></summary>

Arbitrum provides different types of rollups and execution environments tailored for various use cases:

#### **Arbitrum One**

* **Description:** The main Arbitrum L2 rollup with full Ethereum compatibility.
* **Best For:** DeFi, NFTs, general dApps.

#### **Arbitrum Nova**

* **Description:** Optimized for **high-throughput and low-cost** transactions using AnyTrust technology.
* **Best For:** Gaming, social apps, microtransactions.

#### **Arbitrum AnyTrust**

* **Description:** Uses **off-chain data availability** with a local DA, 3rd party DA for efficiency.
* **Features:**
  * Custom gas token support.
  * Validium-based solution.
* **Best For:** Enterprise solutions L2.

#### **Arbitrum Orbit**

* **Description:** Allows developers to launch **custom L2 or L3 rollups** with tailored settings.
* **Best For:** Application-specific rollups, custom gas tokens, ecosystem chains.

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<summary><strong>Setup &#x26; Configuration</strong></summary>

<img src="https://1439499438-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fti15D1ubA4vJmpJV8XEc%2Fuploads%2F8tDjtJlMDtK1jknb0Gby%2Farbitrum%20flowchart.jpg?alt=media&#x26;token=25ad7d2a-10e0-4204-a39f-fe3256137ce7" alt="" data-size="original">

* **Sequencer (with ArbOS):** Orders transactions and executes state transitions but does not submit rollup data to L1.
* **Coordinator:** Aggregates L2 transactions into compressed batches before posting them to L1 Ethereum.
* **Node Provider / RPC Interface:** Allows dApps and users to interact with the Arbitrum network.
* **Fraud Proof System:** Handles fraud-proof verification and dispute resolution.
* **Finalized Transactions:** Transactions validated through the fraud-proof mechanism.

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<summary><strong>Configuration Parameters</strong></summary>

* **`max_gas_limit_per_block`**: Determines the maximum gas allowed in each Arbitrum block.

*(Applies to Arbitrum One & Orbit but differs for Nova & AnyTrust)*

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<summary><strong>Why is my bridge withdrawal taking so long?</strong></summary>

Arbitrum has a 7-day challenge period for fraud-proof verification.

* During the 7-day challenge period, anyone can submit fraud proofs if they detect an invalid state transition.
* If no fraud is detected, the transaction is finalized, and funds become available on Ethereum L1.
* This mechanism ensures that Arbitrum remains secure without needing real-time computation on L1.

#### Faster Withdrawal Alternatives

A faster alternative is to use liquidity providers like Hop Protocol or Across Protocol. Waiting 7 days can be inconvenient, users can use third-party liquidity providers that offer fast exits by fronting the withdrawn funds.

* **Hop Protocol** – Bridges assets instantly by using a network of liquidity providers.
* **Across Protocol** – Provides rapid transfers across chains using bonded relayers.

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<summary><strong>Does Arbitrum support EIP-1559?</strong></summary>

Yes, Arbitrum does support EIP-1559.

#### **What Does This Mean for Developers?**

* **Gas estimation must be adjusted** – Arbitrum does use a "base fee" + "priority tip" structure.
* **Wallets may display fees differently** compared to Ethereum mainnet.

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<summary><strong>What happens if the Arbitrum Sequencer goes offline?</strong></summary>

* **Failsafe Mode:** Users can submit transactions directly to Ethereum L1.
* **Censorship Resistance:** If the sequencer fails to include a transaction, users can force inclusion after **24 hours**.
* **Multiple Sequencer Support:** A new sequencer can be activated if the primary one is down.

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<summary><strong>Validators &#x26; Security Model</strong></summary>

Arbitrum uses a **three-tier validator model** to maintain security and detect fraud:

#### **Security Mechanism:**

* **Punishment for Fraud:** Malicious validators lose their stake.
* **Observers Earn Rewards:** If they catch fraudulent activity.

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