Horde and Alliance character

Hello everyone,
Is it authorized to have a Horde and an Alliance character on the same account ?
Is it authorized to have a Horde character on a account and have a second account with an Alliance character on it ?
Is it authorized to have a Horde and an Alliance character on the same account ?
Is it authorized to have a Horde character on a account and have a second account with an Alliance character on it ?