There’s really no better guard dog than the Rottweiler, primarily because he’s also an excellent watchdog.
Rottweilers are quite smart, but they can be a handful to train. They also require a lot of socialization in order to be well-adjusted family dogs.
Temperament: Rottweilers are a powerful breed with well-developed genetic herding and guarding instincts. Potentially dangerous behaviour in Rottweilers usually results from irresponsible ownership, abuse, neglect, or lack of socialisation and training. However, the exceptional strength of the Rottweiler is an additional risk factor not to be neglected. It is for this reason that breed experts declare that formal training and extensive socialisation are essential for all Rottweilers. According to the AKC, Rottweilers love their owners and may behave in a clownish manner toward family and friends, but they are also protective of their territory and do not welcome strangers until properly introduced. Obedience training and socialisation are required. – Wikipedia