# Finding the longest attestation slot gap

## :fast\_forward: Quick steps guide

{% hint style="info" %}
The following steps align with our [mainnet guide](/spanish/coins/overview-eth/guide-or-how-to-setup-a-validator-on-eth2-mainnet.md). You may need to adjust file names and directory locations where appropriate. The core concepts remain the same.
{% endhint %}

### :dagger: Why do I want to calculate the longest attestation slot gap?

* Your validators are assigned duties to attest and propose blocks.
* Understanding the schedule of your validator's duties better, you can find the best time to plan consensus/execution client updates, system reboots or outages.
* Since the Altair Hard Fork, checking sync committee membership is a must before performing any maintenance. This will give you up to [\~27 hours of advanced notice](https://github.com/ethereum/consensus-specs/pull/2453) in case your validators have been selected for sync committee duties.

### :robot: Pre-requisites

* python3
* validator index number(s) -- Lookup on [https://beaconcha.in/](https://beaconcha.in) or [https://beaconscan.com/](https://beaconscan.com)
* Works with **Lighthouse / Teku / Prysm** currently

{% hint style="success" %}
:sparkles: Kudos to **pietjepuk2** on Discord for authoring this process.
{% endhint %}

### :construction: How to Run the Validator Duties script

1\. Install python3

```
sudo apt update && sudo apt-get install python3
```

2\. Download [pietjepuk2](https://gist.github.com/pietjepuk2)'s `get_validator_duties.py` python script.

{% tabs %}
{% tab title="Lighthouse | Teku" %}

```bash
cd $HOME
wget https://gist.githubusercontent.com/pietjepuk2/eb021db978ad20bfd94dce485be63150/raw/cc874b3035f97495416353f203d70477b31ab05d/get_validator_duties.py
```

{% endtab %}

{% tab title="Prysm" %}

```bash
cd $HOME
# modified by mohamedmansour for prysm
wget https://gist.githubusercontent.com/mohamedmansour/9a82071802ffd58bef7ab5db530f23fd/raw/d48a3f0948cf2ae8cf571b42d50f80d66841118f/get_validator_duties.py
```

{% endtab %}
{% endtabs %}

3\. Enter your validator index numbers as parameters to the python script.

```bash
python3 get_validator_duties.py <validator index number(s)>
# Example
# python3 get_validator_duties.py 1000 1001 1002 1003
```

Sample Output showing the longest gap in seconds, # of slots and time range.

> Longest gap (first):
>
> 120.0 seconds (10 slots), from 13:37:35 until 13:39:35

{% hint style="info" %}
:question:**Troubleshooting:**

* The python script calls the `http API` on port 5052.
* Ensure the `http API` is enabled for your consensus layer client.
  * teku: `--rest-api-enabled=true`
* Teku by default uses port 5051, rather than 5052. Search and replace the port number before using.
  {% endhint %}

{% hint style="warning" %}
:fire: **Script Usage Caveats**:

* This version does not include block proposals, although the odds of having one scheduled are really low of course.
* Block proposal duties are only known for the current epoch, whereas attestation duties are known for the current and next one.
  {% endhint %}

{% hint style="success" %}
Nice work. Now you now the best gap to avoid missing any validator duties.
{% endhint %}

## :robot: Start staking by building a validator <a href="#start-staking-by-building-a-validator" id="start-staking-by-building-a-validator"></a>

### Visit here for our [Mainnet guide](https://www.coincashew.com/coins/overview-eth/guide-or-how-to-setup-a-validator-on-eth2-mainnet)

{% hint style="success" %}
Congrats on completing the guide. ✨

Did you find our guide useful? Send us a signal with a tip and we'll keep updating it.

It really energizes us to keep creating the best crypto guides.

Use [cointr.ee to find our donation](https://cointr.ee/coincashew) addresses. 🙏

Any feedback and all pull requests much appreciated. 🌛
{% endhint %}

## :jigsaw: Reference Material

{% embed url="<https://gist.githubusercontent.com/pietjepuk2/eb021db978ad20bfd94dce485be63150/raw/cc874b3035f97495416353f203d70477b31ab05d/get_validator_duties.py>" %}

<https://gist.github.com/mohamedmansour/9a82071802ffd58bef7ab5db530f23fd>


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://www.coincashew.com/spanish/coins/overview-eth/guide-or-how-to-setup-a-validator-on-eth2-mainnet/part-ii-maintenance/finding-the-longest-attestation-slot-gap.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.