# What are Validating Nodes (VNs)

**Validating Nodes (VNs)** play a crucial role in ensuring that all transactions in the system are processed fairly, accurately, and transparently. In a decentralized network, there is no single authority to oversee transactions, so VNs act as referees, ensuring the system runs correctly.

<figure><img src="/files/KiPj17MxJNoe7uuxSJ3K" alt=""><figcaption><p>Validating Node (VNs) Monitoring</p></figcaption></figure>

## **Validating Nodes (VNs) main responsibilities:**

### **Verifying Transactions**

VNs check that orders processed by the system are accurate, whether they come from the off-chain sequencer or the decentralized (on-chain) path. Their role is to verify that each transaction in an epoch (10-second time window) is processed fairly and correctly.

### **Ensuring Order Consistency**

VNs keep an eye on both **on-chain** and **off-chain** processes, checking that:

1. Orders submitted off-chain (directly to the sequencer) and those posted on-chain match and are accurate.
2. Transactions processed by the centralized sequencer are correct and in the right sequence. If the sequencer processes these orders inaccurately, it must be challenged too.

### **Raising Challenges**

If VNs detect a discrepancy, whether it’s between on-chain and off-chain data, or within off-chain orders processed by the sequencer, they can [**raise a challenge**](#raising-challenges). This challenge allows for further investigation to maintain fairness in the system.


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