How do you determine a dipole?
Any separation of charge is a dipole. A permanent dipole results from an unequal distribution of charge eg. in a covalent bond. A covalent bond between two of the same atoms is not a permanent dipole. But a covalent bond between two different atoms is a permanent dipole. However, if the difference in electronegativity is < 0.5, the dipole can be said to be insignificant. This means that C-H bonds are non-polar. This is convenient in explaining why hydrocarbons do not dissolve in water. It should be noted that a molecule can have many dipoles operating in different directions but no overall dipole or an insignificant overall dipole.
According to the Mastering Chemistry definition, dipole-dipole forces are weak. Though they are stronger than dispersion forces, and technically hydrogen bonds (which are moderate) are a form of dipole-dipole force, dipole-dipole forces in general are relatively weak. Depending on the polarity of the bond (how large the dipole is), they can be extremely weak.