Are enums by default unsigned? [duplicate]

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• Are C++ enums signed or unsigned? 8 answers

enum Color
 {
   GREY = 4294967294,
   RED 
 }

RED is assigned the largest value a 4 byte unsigned int can hold. When I use sizeof to know the size of my enum Color (sizeof (Color)), it prints 4. If I assign -1 to RED, the sizeof prints 8. Does that mean an enum is by default unsigned?