Another valuable exercise for improving your knowledge of the fretboard is to find all possible octaves of any given note. Remember that an octave is the distance between any note and its next repeat at a higher or lower pitch.
An example of this would be the note C#, which can be found at the 9th and 21st frets on the sixth string, the 4th and 16th frets on the fifth string, the 11th fret on the fourth string, the 6th and 18th frets on the third string, the 2nd and 14th frets on the second string, and the 9th and 21st frets on the first string.
These positions are shown in the following diagram. Practice choosing notes at random and finding each one in all possible positions, until you are confident you can instantly find any note in any position.