Which of the following is not a type of logic gate

Logic gates are the basic building blocks of digital circuits, and each one performs a specific Boolean operation on one or more binary inputs to produce a single output. The standard set of logic gates taught at this level includes AND, OR, NOT, NAND, NOR, XOR, and XNOR.

AND, OR, and XOR (exclusive OR) are all genuine, well-defined logic gates. AND produces a true output only when all its inputs are true, OR produces a true output when at least one input is true, and XOR produces a true output only when its inputs differ from each other.

There is no standard logic gate called "DOR" in digital electronics; it does not appear in any recognised classification of logic gates and does not correspond to any defined Boolean operation. Because the other three options are all established gates with clear definitions, the term that does not belong to this group is the one with no real definition in logic gate theory.

Exam tip: when identifying logic gates, check whether the term matches one of the standard names (AND, OR, NOT, NAND, NOR, XOR, XNOR); any name outside this list is not a genuine logic gate.