Just as important as installing the ledger correctly, installing the posts is the second most important step. Building code now dictates that ALL deck posts be mounted on brackets which elevate the post above the ground, on concrete footings. This means your post cannot be buried in the ground!! This causes rot on every type of wood and should be avoided.
An Unfortunate victim of common deck construction
The Right way to Install a Post to Building Code
Post bases wrapped in cedar facia to conceal fasteners