John's disciples in Ephesus

How could John the Baptist have disciples in Ephesus? How could they know John's baptism but not the Holy Spirit? What did Apollos really know about Jesus? We can get answers when we realize how John's teachings spread through his disciples, who as the forerunner to the Messiah prepared his students for His coming. Apollos, being a gifted student of John the Baptist, understood the things concerning Jesus, but needed to understand the way of God more accurately, because he did not know the fullness of the revelation of the gospel. Thus, a deficient knowledge of God must be corrected. It is absolutely crucial to have a thorough, personal knowledge of Jesus Christ.