What do these geth --rpcapi parameters mean: db and net?

Question

Many times in different guides I met the following string to start geth:

geth --rpc --rpcapi="db,eth,net,web3,personal"

Here we can find commands provided by admin, personal, eth options. But what do "db" and "net" mean and allow? And is "eth" option needed in case of web3j requests?

Answer 1

db enables these functions:

db_putString
db_getString
db_putHex
db_getHex

net enables these functions:

net_version
net_peerCount
net_listening

As stated in: https://github.com/ethereum/wiki/wiki/JSON-RPC