An XNOR gate is an inverted XOR gate. This is the same as using the output of the XOR gate as the input to the NOT gate. This means that the XNOR gate returns TRUE only when both inputs are the same state. Either both are TRUE or both are FALSE.

Input 1Input 2Output
Input 1
0
Input 2
0
Output
1
Input 1
0
Input 2
1
Output
0
Input 1
1
Input 2
0
Output
0
Input 1
1
Input 2
1
Output
1