strangely getsockopt() return 4 instead of 1 for some options

test_getsockopt.c

//...
	struct addrinfo hints, *res;
	int sockfd;

	memset(&hints, 0, sizeof hints);
	hints.ai_family = AF_INET;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_flags = AI_PASSIVE;
	
	int result = getaddrinfo(NULL, "3490", &hints, &res);
	
	sockfd = socket( res->ai_family, res->ai_socktype, res->ai_protocol );
	
	int optval1;
	socklen_t optlen1 = sizeof(optval1);
	int resultO1 = getsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &optval1, &optlen1 );
	if( resultO1 < 0 )
	{
		printf( "## fail getsockopt()\n" );
		printf( "err %i: %s\n", errno, strerror(errno) );
		exit(1);
	}
	printf( "SO_REUSEADDR = %i\n", optval1 );

	int optval2 = 1;
	int optlen2 = sizeof(optval2);
	int resultO2 = setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &optval2, optlen2 );
	if( resultO2 < 0 )
	{
		printf( "## fail setsockopt()\n" );
		printf( "err %i: %s\n", errno, strerror(errno) );
		exit(1);
	}
	printf( "SO_REUSEADDR changed = %i\n", resultO2 );

	int optval3;
	socklen_t optlen3 = sizeof(optval3);
	int resultO3 = getsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &optval3, &optlen3 );
	if( resultO3 < 0 )
	{
		printf( "## fail getsockopt()\n" );
		printf( "err %i: %s\n", errno, strerror(errno) );
		exit(1);
	}
	printf( "SO_REUSEADDR = %i\n", optval3 );
//...


//output
/*
SO_REUSEADDR = 0
SO_REUSEADDR changed = 0
SO_REUSEADDR = 4
*/