Answer: John’s baptism was from heaven, and he therefore baptized by the authority or in the name of God.  He baptized Christ, although Christ was sinless, to fulfill all righteousness; that is, to do the righteous will of God, to point forward to Christ’s atoning death for our sins and his resurrection for our justification, and to show the example  we are to follow. 

Though Christ had no sin of his own, he was the representative of his sinful people.  He was a real man, as well as the real God, and he was baptized and labored and suffered and bled and died and rose as a man. 

Some of John’s disciples whom he had baptized followed Christ, and were not baptized in water again, so far as we are told in the Scriptures.  The baptisms performed by Christ’s disciples before his crucifixion were undoubtedly in the name or by the authority of God (Christ is God), and did not have to be repeated, and were therefore substantially the same as those performed by his apostles after his ascension, though the form of words used was not probably the same; the Scriptures do not tell us the form of words used in the baptisms performed by John or in those performed by the disciples of Christ before his crucifixion, and it is, therefore, not necessary for us to know that form of words.  An attempt to be wise above what is written, and speculation upon things that the Lord has not revealed to us, are not only unprofitable, but injurious to the people of God, tending, not to edify and unite, but to confuse and divide them.” (Hassell in Questions and Answers by R..H. Pittman 1935)