I understand PoW uses gas to counter a DDoS attack. What about PoA? Is gas also used in PoA networks?
Proof of Authority networks still use gas to power Contract calls and Transactions.
EVM-based PoA chains use gas because gas is an integral part of the EVM. Other PoA chains might use different spam protection mechanisms or--in setups where the authorities trust each other as well as all transaction senders--go without one altogether.