When the connect_to_testnet script is invoked it will first verify that
the genesis file of the testnet hasn't changed. If it has changed, any
previously created database associated with the testnet will be erased.
To facilitate this, the genesis file of each network is written to the
data folder of the beacon node. The beacon node will refuse to start if
it detects a discrepancy between the data folder and any state snapshot
specified on the command-line.
Since the testnet sharing spec requires us to use SSZ snapshots, the Json
support is now phased out. To help with the transition and to preserve the
functionality of the multinet scripts, the beacon node now supports a CLI
query command that can extract any data from the genesis state. This is
based on new developments in the SSZ navigators.
Zahary Karadjov