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
kovan (only fast sync and may fail if pWASM transactions appear)
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
This is a Clique-PoA based testnet supported by Geth and Nethermind. It has a 15 seconds delay between blocks.
Nethermind.Runner --config rinkeby