In case of proof of work consensus mechanism miners compete with each other to solve the cryptographic puzzle and once a miner found the answer of puzzle , he will broadcast it to all the nodes participating in blockchain network. Majority of miners need to agree and validate the block using answer sent by miner and block is appended to blockchain.
In case of proof of authority, how sealers/signers validate blocks?
EDIT 1 :
This question suggest that in case of Proof of Authority consensus mechanism signers sign blocks in round robin fashion ,Agreed ! My question is what procedure signers follow to sign a valid block? How do they identify invalid block? In case of proof of work node can validate block based on answer of cryptographic puzzle sent by miner.