By default Nethermind launches with mainnet network configuration but you can sync any of the below networks by adding a command line switch:
Network name can be any of the following
This is the main public Ethereum network secured by the ethash PoW algorithm.
Nethermind.Runner --config mainnet
This is a Clique-PoA based testnet supported by all major clients. It has a 15 seconds delay between blocks that are sealed by Goerli validators.
Nethermind.Runner --config goerli
This is a test network secured by ethash PoW algorithm which resembles mainnet most closely but is prone to hashrate-based attacks.
Nethermind.Runner --config ropsten