Internet-related issues have influenced how civic knowledge is educated and measured. The International Civic and Citizenship Education Study (ICCS) is a well-known large-scale assessment concerning how civic knowledge is educated and measured globally. Regardless of the emerging roles of internet access and usage, the influences of internet access on civic knowledge have yet to be investigated in ICCS research. Hence, this study aims to study whether the multiple-choice items in the civic knowledge test of ICCS 2016 are affected by internet access, what causes the effect, and to what degree Internet access influences the measurement. Results indicated that the ICCS civic knowledge test included six differential item functioning (DIF) items on internet access, of which five favored families with internet access, and one favored families without internet access. In addition, the primary source of DIF items was highly related to socioeconomic status. Overall, the students in families where the internet was available possessed higher civic knowledge than the students who were not. In conclusion, this study provides evidence of item inequivalence and identifies suspicious sources. These results can be used as a basis to investigate related research on digital learning, online teaching, and social media engagement in civic literacy.