Stephane

The scan is scanning the whole index (the whole table in the case of a clustered index) whereas a seek goes straight to where it needs to go to find the data.  Therefore a seek is usually desirable.  I think the reason for this is that the query optimizer can't use the clustered index to work out the "<= ipTo" part of the "BETWEEN ipFrom and ipTo" clause.  Therefore I would recommend you create a non-clustered index on ipTo (assuming that your clustered index is created on ipFrom and ipTo in that order).

John