Arbitrum Rollup FAQ

1. What Orbit modes do you support?

	L3 Orbit	L2 Orbit*
Testnet parent chains	Arbitrum Sepolia	Sepolia
Mainnet parent chains	Arbitrum One	Ethereum
Data availability	AnyTrust	Ethereum DA / AnyTrust

We will also be rolling out other integration options such as Celestia, EigenDA and Avail soon. *Do note that L2 Orbit chain deployment requires a 10% sequencer fee sharing agreement with Arbitrum Foundation as stated in the Arbitrum Expansion Program.

2. What is included in the standard setup?

Parameter	Value
Orbit chain	1 sequencer / batch poster / staker / validator node
RPC / WS data	1 or more load-balanced full nodes 1 feed relay node to allow you to host your own full nodes
Block explorer	Standard Blockscout v2 application
AnyTrust DA	1 DA server to store transaction data 1 or more load-balanced mirror nodes to serve data read requests

4. What is the rollup setup process like? You can refer to the Arbitrum quickstart guide for details: https://docs.arbitrum.io/launch-orbit-chain/orbit-quickstart In brief, the steps are:

   1. Rollup registration on Arbitrum’s rollup factory contract

   2. Deployment of the nodes for your chain

   3. Token bridge creation on Arbitrum’s token bridge factory contract

   4. Some final configuration actions on the Orbit chain

5. Is custom gas token supported? Yes. Please see this page for more information.

6. Is custom stake token supported? At this time, custom stake tokens are not yet supported.

   We’d also like to emphasise that the stake token being referred to here is the token that the sequencer (validator) must stake on the parent chain in order to post regular assertions and be subjected to slashing if he/she misbehaves (detected via fraud proof). It is not a stake token in the traditional sense of earning rewards. Also do note that sequencer slashing with alt-DAs is still work-in-progress, do see Celestia Blobstream and EigenDA M1/M2 integration.

7. Who receives the fees on the Orbit chain? There are three kinds of fees:

   • L2 surplus fee (network fee)

   • L2 base fees (infrastructure fee)

   • L1 fee rewards

   The receiver of these fees are all configurable to any addresses of your choosing. Please refer to this page for more information.

   Additionally, the batch poster account also gets reimbursed for every batch posting receipt that arrives on the chain.

8. What parameters can we configure for our Orbit chain?

   You can provide us with your preferred:

   • Chain ID (if no preference, we’ll generate a random ID)

   • Network name

   • Custom gas token adress*

   • Fee receiver address

   For mainnets, you also need to provide us with:

   • Chain operator address (for sending chain configuration transactions)

   • Challenge period (for withdrawals)

   *If you are planning to use a custom gas token address, please also send some tokens to us for the chain setup.

9. Can I quickly try out an Orbit rollup somewhere? We provide a public testnet that you can use to test out Orbit: https://rollup-info.altlayer.io/public/orbit_demo_testnet

10. Can we host our own full nodes? Yes, and in fact hosting your own full nodes is recommended if you have query-intensive applications for your chain, such as an indexer. Upon request, we will provide you with the scripts for launching your own full nodes.

11. Can we use our own domain for the chain URLs? Yes, you can CNAME the RPC, websocket (if any) and explorer URLs to your own domain.

    For these customizations, you will need to create CNAME records on your DNS provider. We will provide you the target for these records.

12. Can we customize our block explorer UI? Yes, we can customize settings such as the logos, icons, color scheme, and text content. Please request our Blockscout order form to see all the customizations available.

13. Can I verify contracts on the block explorer? Yes. Please follow this sample for verifying a deployed contract using hardhat or foundry.

14. How are gas fees calculated? It is a sum of the L2 + L1Data fees. L2 fees depend on the L2 activity (the more transactions, the higher the fees) and base fees set by the deployer. L1Data fees depend on the gas fees on Ethereum, which might spike during peak activities (do note L1Data fees will depend on blob space availability on Ethereum post-4844).

    Please note that for Orbit chains requiring custom gas tokens, additional changes to the L1 pricing parameters are required in order to avoid charging users for non-existent L2 base fees.

15. What are our bridging options? You can use the native bridge for Orbit chains (here). Or, you can choose to partner with third-party bridges in our partner list.

16. What can we expect after the chain setup is completed? You will receive a rollup info page containing all the L2 details and links, similar to this. We can also help with transferring the ownership to a multi-sig (gnosis-safe fork hosted by us), if you choose to do so.

17. Do you support migrations to alternative DAs or addition of restaked rollup modules after the Orbit L2/L3 chain is live? We are currently in the midst of adding this capability.

18. Where can I get more information about Arbitrum Orbit? You can refer to https://docs.arbitrum.io/launch-orbit-chain/orbit-gentle-introduction