How does the Ethereum PoW algorithm verify the work?

I've been reading up on the EthHash PoW algorithm but I don't understand quite how the verification process works. I understand that the miners will try and grab a subset of the DAG in the 4GB cache but what exactly are they verifying it against?

I know that the Bitcoin PoW verifies that the answer has a certain number of leading zeros, but I can't really find a good answer on the internet on what exactly the criteria for verification is for EthHash.

Thanks in advance,