# Basic replica node

**Replica nodes** simply validate and replicate blocks that the network has already produced. They are the most common type of full node, and running one does not require staking anything.

## On the mainnet

### Starting melnode

Running the `melnode` command without any arguments starts an instance running on the mainnet.

```shell-session
melnode
```

You will see output looking like this:

```shell-session
[2022-12-12T16:40:48Z INFO  melnode] melnode v0.13.2 initializing...
[2022-12-12T16:40:48Z DEBUG melnode::args] database opened at "/home/user/.melnode/"
[2022-12-12T16:40:48Z INFO  melnode::storage::storage] HIGHEST AT 0
[2022-12-12T16:40:48Z DEBUG melnode::args] node storage opened
[2022-12-12T16:40:48Z INFO  melnode] bootstrapping with [185.177.126.98:41814]
[2022-12-12T16:40:48Z DEBUG melnode::protocols::node] starting to listen at 0.0.0.0:41814
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 1 of length 215 in 1.08ms (insert 9.54ms)
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 2 of length 215 in 0.51ms (insert 0.26ms)
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 3 of length 215 in 0.43ms (insert 0.21ms)
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 4 of length 215 in 0.45ms (insert 0.22ms)
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 5 of length 215 in 0.43ms (insert 0.24ms)
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 6 of length 215 in 0.44ms (insert 0.23ms)
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 7 of length 215 in 0.44ms (insert 0.24ms)
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 8 of length 215 in 0.46ms (insert 0.18ms)
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 9 of length 215 in 0.46ms (insert 0.15ms)
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 10 of length 215 in 0.46ms (insert 0.16ms)
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 11 of length 215 in 0.46ms (insert 0.16ms)
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 12 of length 215 in 0.44ms (insert 0.25ms)
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 13 of length 215 in 0.46ms (insert 0.20ms)
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 14 of length 215 in 0.64ms (insert 0.25ms)
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 15 of length 215 in 0.46ms (insert 0.22ms)
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 16 of length 215 in 0.47ms (insert 0.13ms)
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 17 of length 215 in 0.48ms (insert 0.13ms)
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 18 of length 215 in 0.47ms (insert 0.23ms)
[2022-12-12T16:40:48Z DEBUG melnode::storage::storage] applied block 19 of length 215 in 0.48ms (insert 0.13ms)
```

{% hint style="warning" %}
There is an optional flag `--index-coins` that is recommended. Certain coin-related RPCs will be disabled if this flag is not set. Do note that the indexer will take up extra memory.
{% endhint %}

It will take *quite* a long time to synchronize all the blocks from the network (usually 10+ hours as of April 2024).

### Participating in peering

{% hint style="warning" %}
To participate in peering, you must have a publicly reachable IP address. Most home internet setups do not give you a public IPv4 address!
{% endhint %}

By default, `melnode` doesn't do much other than downloading blocks. The default listening port is `localhost:41814`: since this is on localhost, no other computers can connect to the node.

To actually contribute to block propagation on the network, you need to expose `melnode` to other networks:

```shell-session
melnode --listen [::1]:41814 --advertise auto
```

We add two flags:

* `--listen [::1]:41814` listens on port 41814 on all network interfaces
* `--advertise auto` automatically guesses our public IP address for incoming connections on the P2P network

If this works, you should soon see output like:

```shell-session
[2022-12-12T16:40:48Z DEBUG melnode::network] incoming connection from 100.64.3.2!
```

indicating that you are helping other nodes connect to the network.

## On the testnet

### Basic functionality

To replicate testnet blocks, add `--network testnet` to any `melnode` command:

```shell-session
melnode --network testnet
```

### Faucets and staking

A distinct feature of the testnet is that **faucets** can be used to generate "free money", which can then be used to test consensus and staking (future feature).


---

# 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://docs.melproject.org/developer-guides/run-a-full-node/basic-replica-node.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.