[Ethereum] how to connect “Kovan” or “Rinkeby” from geth

Sepolia

• Proof of Work (Ethash)
• Best reproduces the current Ethereum production environment (PoW)
• Website: https://sepolia.dev/
• Resources: https://github.com/goerli/sepolia

Goerli

• Proof of Authority (Clique)
• Most stable for application developers (15s blocktime, no downtimes)
• Website: https://goerli.net/
• Resources: https://github.com/goerli/testnet

Ropsten (deprecated in 2022!)

• Proof-of-Work (Ethash)
• Supported by all clients until 2022
• Will no longer receive protocol upgrades

Rinkeby (deprecated in 2022!)

• Proof of Authority (Clique)
• Supported by all clients until 2022
• Will no longer receive protocol upgrades

Kovan (deprecated in 2019!)

• Proof of Authority (Authority Round)
• Supported by OpenEthereum and Nethermind only
• Minimally maintained by the Gnosis/xDAI community

If you need a stable testnet with support on multiple clients go with Goerli. If you need to have conditions as close as possible to mainnet, but less stability than Goerli, choose Sepolia.

Detailed version below:

Ropsten

• PoW testnet
• History:
  • Started in November 2016. Named after a subway station in Stockholm.
  • Was DoS attacked in February 2017 which made synching slow and made clients consume a lot of disk space.
  • Was revived in March 2017 and became usable again.
• Pros:
  • Best reproduces the current production environment, i.e. system and network conditions on the live Ethereum mainnet, because it's PoW net.
  • Can be used with all clients.
  • Ether can be mined. Or requested from a faucet:
    • https://faucet.metamask.io/
    • http://faucet.ropsten.be:3001
    • https://faucet.bitfwd.xyz/
    • What public test-networks and faucets exist?
• Cons:
  • Not immune to spam attacks. Because of this it's less stable.
• Network id: 3
• Block time: sub-30 seconds
• Commands:
  • geth --ropsten
  • besu --network ropsten
• Explorer https://ropsten.etherscan.io/
• Github https://github.com/ethereum/ropsten

Görli

• Clique PoA testnet started by the Goerli Initiative
• History:
  • Started in November 2018 after a proposal by Afri. It's a testnet that has the goal of being both widely usable across all client implementations supporting Clique PoA engine (EIP-225), and robust enough to guarantee consistent availability and high reliability.
• Pros:
  • Supported by multiple clients (including Geth, Pantheon, Nethermind and Open Ethereum)
• Chain id: 5
• Network id: 5
• Block time: 15 seconds on average
• Status Dashboard: https://stats.goerli.net/
• Explorer https://goerli.etherscan.io/
• Github https://github.com/goerli/testnet
• Website https://www.goerli.net

I found a work around by using the zero client provider. It works in a stable manner for the Mainnet and Kovan RPC connections provided by Infura.