[chord] lookup query in chord

[sri wahjuni]

hi, i just starting study the chord protocol. I still confused about the number of hops envolved in a lookup query.  some paper said that for an overlay consist of N nodes, the number of hops is O(logN) but some other paper said it is O(log2 N) -- the second is base 2 logarithm. In the end of Chord's first paper (2001) also presented it in base-2 logarithm. Would anyone explain about this? 
Thank you very much for any help
Kind regards
Wahjuni