Dreams featuring snakes can often symbolize various aspects of transformation, fear, or hidden emotions. In your dream, the big white and black scaled snake with a cobra head could represent a powerful force or situation in your life. The act of it eating a smaller snake might suggest themes of dominance or the resolution of competition, possibly reflecting a struggle between different aspects of yourself or conflicts in your waking life.

The presence of the brown snake looking at the entrance of your backhouse door might symbolize a perceived threat or anxiety about something that is on the verge of entering your life but hasn't yet. Since it didn't enter and harm the domestic animals, it could indicate that while there may be fears or worries, they may not come to fruition or may be manageable.

Overall, this dream could be urging you to confront and acknowledge your fears or conflicts while also reminding you to remain vigilant about potential threats in your surroundings, but not to let these fears control you. Reflecting on any current situations that may feel threatening or competitive could provide further insights.