You should write the name of the Airport or border that you used to enter the US. For some people, this airport might be a non-US airport like Abu Dhabi where they complete the US immigration process at Abu Dhabi airport itself. I would suggest writing either the “Port of Entry/Exit” as “MAA – ABU DHABI INTL” or the name of the US airport where you landed first. For example, if you landed at Washington Airport after completing the immigration process at Abu Dhabi airport, your i94 record will show the “MAA – ABU DHABI INTL” as the port of entry. You can then either write "Washington Airport" or "MAA – ABU DHABI INTL".