The Internet Addiction Scale.
The internet addiction scale is a 11 item questionnaire.
Items are scored on a SD-SA (1-5) scale, with the total scale score calculated as a sum of the items.
Faraci, P., Craparo, G., Messina, R. and Severino, S. (2013). Internet Addiction Test (IAT): Which is the Best Factorial Solution?. Journal of Medical Internet Research, 15(10), p.e225.