Border Zone Reasonableness Restoration Act of 2018 This bill revises the border zone area in which Department of Homeland Security (DHS) officers may take certain immigration-related actions without a warrant. The Immigration and Nationality Act is amended to permit DHS officers to take the following actions without a warrant in order to patrol the border and prevent the illegal entry of persons: board and search any vessel within U.S. territorial waters and any railway car, aircraft, conveyance, or vehicle within 25 air miles from an external U.S. boundary (a vehicle may not be stopped at a fixed checkpoint beyond 10 air miles from such boundary without reasonable suspicion that an occupant is illegally in the United States); and access private lands, but not dwellings, within 10 air miles from such boundary. DHS may establish, and shall certify to Congress, that: (1) a distance of up to 100 air miles is required in a sector for conveyance searches, and (2) a distance of up to 25 air miles is required in a sector for private land access. In making such certifications DHS shall consider reasons such as land topography, transportation, or consultations with state, local, and tribal governments.